11 261 Exponent Status

Great Internet Mersenne Prime Search
GIMPS
Finding World Record Primes Since 1996

PrimeNet Exponent Status

M_n

Details

Composite, with 2 known prime factors. Cofactor is composite.

Trial Factored to 2⁶⁸

TF target 2⁴⁴

Factored

Factor	Digits	Bits	Date
450953250434657	15	48.7	old
399280513235788226399873081	27	88.4	2008-08-29 02:24:27

P-1 factors

Date	Factors	B1	B2
2022-12-30	No new factors discovered	100000000000	122192573512709696

ECM

Digits	B1	Curves
25	50000	280 / 280
30	250000	640 / 640
35	1000000	1566 / 1566
40	3000000	4588 / 4588
45	11000000	5783 / 9201

Estimated T-Level: 43.1 ⓘ

TF below 2^138 is very unlikely to find new factors due to ECM effort.

Status	Proof	Date	User	Residue	Number of known factors	Shift	Type	Base
Verified	No proof (small exponent)	2017-09-21	Oliver Kruse	52FC8BBD39FAA2DE	2	0	1	3
Verified	No proof (small exponent)	2017-10-02	kkmrkkblmbrbk	52FC8BBD39FAA2DE	2	0	1	3
Verified	No proof (small exponent)	2017-12-07	ATH	52FC8BBD39FAA2DE	2	7781	1	3
Verified	No proof (small exponent)	2020-04-17	Oliver Kruse	301EAD312EF4501C	2	5060	5	3
Verified	No proof (small exponent)	2024-07-01	kkmrkkblmbrbk	301EAD312EF4501C	2	6248	5	3

History

Date	User	Type	Result
2025-02-21	masser	NF-PP1	Start=175/37, B1=640000000, B2=639360000000
2025-02-13	masser	NF-PP1	Start=6/5, B1=640000000, B2=639360000000
2025-01-24	masser	NF-PP1	Start=2/7, B1=640000000, B2=639360000000
2024-07-01	kkmrkkblmbrbk	C-PRP	M11261/399280513235788226399873081/450953250434657 : 301EAD312EF4501C
2022-12-30	-anonymous-	F-PM1	Factor: 399280513235788226399873081 / B1=100000000000, B2=122192573512709700
2020-04-17	Oliver Kruse	C-PRP	M11261/450953250434657/399280513235788226399873081 : 301EAD312EF4501C
2017-12-07	ATH	C-PRP	M11261/450953250434657/399280513235788226399873081 : 52FC8BBD39FAA2DE
2017-10-02	kkmrkkblmbrbk	C-PRP	M11261/450953250434657/399280513235788226399873081 : 52FC8BBD39FAA2DE
2017-09-21	Oliver Kruse	C-PRP	M11261/450953250434657/399280513235788226399873081 : 52FC8BBD39FAA2DE
2017-09-21	Oliver Kruse	C-PRP	M11261/450953250434657/399280513235788226399873081 : 52FC8BBD39FAA2DE
2016-09-07	kkmrkkblmbrbk	NF-PM1	B1=100000000, B2=10000000000, E=12
2008-08-29	-anonymous-	F-ECM	Factor: 399280513235788226399873081