1 961 147 Exponent Status

PrimeNet Exponent Status

M_n

Status

Details

Composite: proven not-prime with both PRP and Lucas-Lehmer tests

No factors below 2⁶⁸

TF target 2⁶²

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

P-1

B1 =	40000000
B2 =	153811772400

ECM

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

Estimated T-Level: 25.8 ⓘ

Status	Date	User	Residue	Shift
Verified		Allan Schrum	B2822A3E532A14FB	0
Verified	1999-01-17	David Underbakke	B2822A3E532A14FB	866994
Verified	2015-07-03	MadPoo	B2822A3E532A14FB	665492

Status	Date	User	Residue	Shift	Type	Base
Verified	2025-09-02	Kriesel	E4053777F5A9384B	0	1	3

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	E4053777F5A9384B PRP proof power = 6 PRP: Verified Proof certified good
2022-12-06	RichD0	NF-PM1	B1=40000000, B2=153811772400
2022-08-15	masser	NF-PP1	Start=2/7, B1=1500000, B2=52500000
2019-05-14	chuenkit	NF	no factor from 2^67 to 2^68
2018-11-26	Joss	NF-PM1	B1=1961147, B2=245143375, E=12
2018-05-16	Joss	NF-PM1	B1=1961147, B2=196114700, E=12
2018-03-04	Joss	NF-PM1	B1=1961147, B2=120000000, E=12
2018-02-13	Joss	NF-PM1	B1=1961147, B2=60000000, E=12
2018-01-29	Joss	NF-PM1	B1=1961147, B2=30000000, E=12
2018-01-08	TJAOI	NF	no factor from 2^66 to 2^67
2016-02-23	Mark Rose	NF	no factor from 2^62 to 2^63
2016-02-23	Mark Rose	NF	no factor from 2^61 to 2^62
2016-02-23	Mark Rose	NF	no factor from 2^58 to 2^60
2015-09-08	ramgeis	NF	no factor from 2^65 to 2^66
2015-07-03	MadPoo	C-LL	B2822A3E532A14FB
2015-04-19	lycorn	NF	no factor from 2^64 to 2^65
2015-04-19	lycorn	NF	no factor from 2^63 to 2^64
2011-08-27	GrunwalderGIMP	NF	no factor from 2^1 to 2^63
2011-04-10	kurly	NF-PM1	B1=1000000, B2=30000000, E=12
2010-01-09	S485122	NF	no factor from 2^60 to 2^61

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