8 221 Exponent Status

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

PrimeNet Exponent Status

M_n

Status

Details

Composite, with 6 known prime factors. Cofactor is composite.

Factored

Factor	Digits	Bits	Date
920753	6	19.8	old
9667897	7	23.2	old
18480809	8	24.1	old
66413573927432647	17	55.9	old
50435132990814087944946096143	29	95.3	old
222671543829866161807730506437010067857087	42	137.4	2025-01-19 06:59:05

ECM

Digits	B1	Curves
25	50000	280 / 280
30	250000	640 / 640
35	1000000	1566 / 1566
40	3000000	4588 / 4588
45	11000000	9201 / 9201
50	44000000	6543 / 16550

Estimated T-Level: 47.0 ⓘ

TF below 2^151 is very unlikely to find new factors due to ECM effort.

Status	Date	User	Residue	Number of known factors	Shift	Type	Base
Verified (Factored)	2017-09-21	Oliver Kruse	E3FBBDFA850BC99D	5	0	1	3
Verified (Factored)	2017-10-02	kkmrkkblmbrbk	E3FBBDFA850BC99D	5	0	1	3
Verified (Factored)	2017-12-07	ATH	E3FBBDFA850BC99D	5	481	1	3
Verified (Factored)	2020-04-17	Oliver Kruse	859897F075C263F2	5	7380	5	3
Verified (Factored)	2024-07-01	kkmrkkblmbrbk	859897F075C263F2	5	6536	5	3
Verified	2025-01-19	nordi	859897F075C263F2	6	4827	5	3

History

Date	User	Type	Result
2025-01-19	nordi	C-PRP	M8221/920753/9667897/18480809/66413573927432647/50435132990814087944946096143/222671543829866161807730506437010067857087 : 859897F075C263F2 PRP: Verified PRP without proof (small exponent)
2025-01-19	nordi	F-ECM	Factor: 222671543829866161807730506437010067857087 / (ECM curve 309, B1=110000000, B2=3103899523725, Edwards Sigma=750835391591304)
2024-07-01	kkmrkkblmbrbk	C-PRP	M8221/18480809/50435132990814087944946096143/66413573927432647/920753/9667897 : 859897F075C263F2 PRP: Verified PRP without proof (small exponent)
2023-09-01	JacobZ	NF-PM1	B1=72000000000, B2=265422648792401100
2021-08-27	Seth_Tr	NF-PM1	B1=400000000
2021-08-25	H Michaelson	NF-PM1	B1=10000000, B2=1000000000
2020-04-17	Oliver Kruse	C-PRP	M8221/920753/9667897/18480809/66413573927432647/50435132990814087944946096143 : 859897F075C263F2 PRP: Verified PRP without proof (small exponent)
2017-12-07	ATH	C-PRP	M8221/920753/9667897/18480809/66413573927432647/50435132990814087944946096143 : E3FBBDFA850BC99D PRP: Verified PRP without proof (small exponent)
2017-10-02	kkmrkkblmbrbk	C-PRP	M8221/920753/9667897/18480809/66413573927432647/50435132990814087944946096143 : E3FBBDFA850BC99D PRP: Verified PRP without proof (not generated)
2017-09-21	Oliver Kruse	C-PRP	M8221/known_factors : E3FBBDFA850BC99D PRP without proof (not generated)