1 996 061 Exponent Status

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

PrimeNet Exponent Status

M_n

Status

Details

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

Factored

Factor	Digits	Bits	Date
19211786140159446601	20	64.1	2015-10-08 11:29:08
43046598300389340001	20	65.2	2009-11-01 14:04:42

ECM

Digits	B1	Curves
25	50000	280 / 280
30	250000	106 / 640

Estimated T-Level: 25.8 ⓘ

TF below 2^81 is very unlikely to find new factors due to ECM effort.

Status	Date	User	Residue	Shift
Verified (Factored)		Erich Steinboeck	D262AF67D23D2CB3	0
Verified (Factored)	1999-02-14	François PERRUCHAUD	D262AF67D23D2CB3	159514

Status	Date	User	Residue	Shift	Type	Base
Verified (Factored)	2025-09-02	Kriesel	6F3E80A137050DAF	0	1	3

Status	Date	User	Residue	Number of known factors	Shift	Type	Base
Verified (Factored)	2017-10-05	Oliver Kruse	861E85C73E8AD401	1	0	1	3
Verified	2017-11-22	kkmrkkblmbrbk	861E85C73E8AD401	2	107069	1	3
Verified	2017-11-22	ATH	861E85C73E8AD401	2	1233999	1	3

P-1 factors

Date	Factor	B1	B2
2015-10-08	19211786140159446601	500000	15000000

History

Date	User	Type	Result
2025-09-03	Jurzal	CERT	PRP Certification CERT proof power = 6 Proof certified good
2025-09-02	Kriesel	C-PRP	6F3E80A137050DAF PRP proof power = 6 PRP: Verified (Factored) Proof certified good
2022-03-09	LordJulius	NF	no factor from 2^1 to 2^60
2017-11-22	ATH	C-PRP	M1996061/43046598300389340001/19211786140159446601 : 861E85C73E8AD401 PRP: Verified PRP without proof (not generated)
2017-11-22	kkmrkkblmbrbk	C-PRP	M1996061/19211786140159446601/43046598300389340001 : 861E85C73E8AD401 PRP: Verified PRP without proof (not generated)
2017-10-05	Oliver Kruse	C-PRP	M1996061/43046598300389340001/19211786140159446601 : 861E85C73E8AD401 PRP: Verified PRP without proof (not generated)
2015-10-08	alpertron	F-PM1	Factor: 19211786140159446601 / (P-1, B1=500000, B2=15000000, E=12)
2009-11-01	James Hintz	F-ECM	Factor: 43046598300389340001
2009-04-24	Rob_Dee	NF	no factor from 2^60 to 2^61