Marin Mersenne 2^P-1
Forgot password?
Great Internet Mersenne Prime Search
Finding World Record Primes Since 1996
Today's Numbers
Teams 1642
Users 271372
CPUs 2769899
GFLOP/s 12675449

Welcome to GIMPS, the Great Internet Mersenne Prime Search

To join GIMPS

Quick Links:
Previous Day Stats
First Prime Tests1758
Verified Prime Tests2699
Newly Factored435

All exponents below 68874119 have been tested and verified.
All exponents below 117776773 have been tested at least once.

Prime95 version 30.19 released

Version 30.19 is now available. ECM stage 2 is now much faster if you can give prime95 lots of memory to use. This is similar to the improvements to P-1 stage 2 in version 30.8. There are other minor bug fixes and tweaks. This is not a required upgrade -- version 30.3 and later can be used to hunt for new Mersenne primes. Should you decide to upgrade, if any workers are currently in ECM or P-1 stage 2 wait for ECM or P-1 to finish before upgrading. If you have any upgrade questions, ask in this thread at Mersenne Forum.


All tests smaller than the 48th Mersenne Prime, M(57885161), have been verified

M(57885161) was discovered eight and half years ago. Now, thanks to the largely unheralded and dedicated efforts of thousands of GIMPS volunteers, every smaller Mersenne number has been successfully double-checked. Thus, M(57885161) officially becomes the 48th Mersenne prime. This is a significant milestone for the GIMPS project.


First-time Lucas-Lehmer Testing Ends

One year ago, first-time PRP primality testing with proofs was introduced. It has been a huge success, saving GIMPS tens of thousands future double-checks. Going forward, the server will no longer make available exponents for first time Lucas-Lehmer tests. Users that have not yet upgraded to prime95 version 30.3 or gpuowl for GPUs should do so. Failure to upgrade will result in unnecessary double-check work. GIMPS has a multi-year backlog of double-checks to work through. There is even a chance that a new Mersenne prime is hidden in all those double-checks.

The server will continue to accept Lucas-Lehmer results. There is no need to worry about any LL tests that are currently underway.


BIG Changes Are Here! Prime95 version 30.3 released.

For almost 25 years, GIMPS has looked for new Mersenne primes by running a primality test on one computer and later running the exact same primality test on another computer to guard against hardware errors having corrupted the first primality test.

A breakthrough by Krzysztof Pietrzak makes it possible to eliminate the second primality test! The first primality test produces a proof file that can be securely verified with less than 0.5% of the work required to re-run the primality test. This breakthrough will nearly double GIMPS' throughput in the long run.

Version 30.3 is now available with PRP proofs. While not a required upgrade, at some point in the future only users running version 30.3 with PRP proofs will be assigned first-time primality tests. Should you run into any problems, support is available at this thread at Mersenne Forum.

Many thanks to Mihai Preda for discovering the paper on the breakthrough and realizing its importance to the GIMPS project. Also, thanks go to Pavel Atnashev for important ideas on adapting the discovery for use by GIMPS.


BOINC users with GPUs can now participate

SRBase has created a BOINC project to hand out trial factoring assignments on large Mersenne numbers. These are very quick work units. To get the most of the BOINC client without any issues, a FAQ at the SRBASE forum is available.

Note that there’s no way to individually credit SRBase users in GIMPS trial factoring stats. All work is credited to GIMPS user SRBase.


51st Known Mersenne Prime Found!

December 21, 2018 — The Great Internet Mersenne Prime Search (GIMPS) has discovered the largest known prime number, 282589933-1, having 24862048 digits. A computer volunteered by Patrick Laroche from Ocala, Florida made the find on December 7, 2018. The new prime number, also known as M(82589933), is calculated by multiplying together 82589933 twos and then subtracting one. It is more than one and a half million digits larger than the previous record prime number.

GIMPS has been on amazing lucky streak finding triple the expected number of new Mersenne primes -- a dozen in the last fifteen years. This prime was even luckier for Patrick Laroche, striking pay dirt on just his fourth try. For years, Patrick had used GIMPS software as a free "stress test" for his computer builds. Less than four months ago he started prime hunting on his media server to give back to the project. By way of comparison, some GIMPS participants have searched for more than 20 years with tens of thousands of attempts but no success. This proves that, with luck, anyone can find the next new Mersenne prime.

The new prime is only the 51st known Mersenne prime ever discovered. Mersenne primes were named for the French monk Marin Mersenne, who studied these numbers more than 350 years ago. GIMPS, founded in 1996, has discovered the last 17 Mersenne primes. Volunteers download a free program to search for these primes, with a cash award offered to anyone lucky enough to find a new prime. Prof. Chris Caldwell maintains an authoritative web site on the largest known primes, and has an excellent history of Mersenne primes.

Patrick is one of thousands of volunteers using free GIMPS software available at Credit for this prime goes not only to Patrick Laroche for running the Prime95 software, Woltman for writing the software, Blosser for keeping the Primenet server running smoothly, and the thousands of GIMPS volunteers that sifted through millions of non-prime candidates.  In recognition of all the above people, official credit for this discovery goes to "P. Laroche, G. Woltman, A. Blosser, et al."

You can read a little more in the press release.

More News and Discussions

GIMPS forumsHere you can chat with fellow GIMPS members, get help with installation questions, learn more about how GIMPS works, etc.

Make Math History!!

You could discover one of the most coveted finds in all of Mathematics - a new Mersenne prime number. We've found fifteen already. Join in on this fun, yet serious research project. All you need is a personal computer, patience, and a lot of luck.

In addition to the joy of making a mathematical discovery, you could win a (USD) $3,000 cash GIMPS Research Discovery Award for each Mersenne prime discovered, and the Electronic Frontier Foundation is offering a $150,000 award to the first person or group to discover a 100 million digit prime number! See how GIMPS will distribute this award if we are lucky enough to find the winning 100 million digit prime.

What are Mersenne primes and why do we search for them?

Prime numbers have long fascinated amateur and professional mathematicians. An integer greater than one is called a prime number if its only divisors are one and itself. The first prime numbers are 2, 3, 5, 7, 11, etc. For example, the number 10 is not prime because it is divisible by 2 and 5. A Mersenne prime is a prime of the form 2P-1. The first Mersenne primes are 3, 7, 31, 127 (corresponding to P = 2, 3, 5, 7). There are only 51 known Mersenne primes.

GIMPS, the Great Internet Mersenne Prime Search, was formed in January 1996 to discover new world-record-size Mersenne primes. GIMPS harnesses the power of thousands of small computers like yours to search for these "needles in a haystack".

Most GIMPS members join the search for the thrill of possibly discovering a record-setting, rare, and historic new Mersenne prime. Of course, there are many other reasons.