Marin Mersenne 2^P-1
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GIMPS
Finding World Record Primes Since 1996

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MnStatusDetails
1556563Composite, with 1 known prime factor. Cofactor is composite.
Factored
FactorDigitsBitsDate
2808141537064898500092167.92013-10-03 05:26:25
ECM
DigitsB1Curves
2550000280 / 280
30250000107 / 640
Estimated T-Level: 25.8 ⓘ
TF below 2^81 is very unlikely to find new factors due to ECM effort.
LL
StatusDateUserResidueShift
Verified (Factored)Danny van der RijnECC760F4F38D3CA80
Verified (Factored)1998-11-07Paul Victor NovareseECC760F4F38D3CA8445856
PRP
StatusDateUserResidueShiftTypeBase
Verified (Factored)2025-09-02KrieselE3DE4DB8546E4301013
PRP Cofactor
StatusDateUserResidueNumber of
known factors		ShiftTypeBase
Verified2017-10-01Oliver KruseFB0426A7B3144B871013
Verified2017-10-30kkmrkkblmbrbkFB0426A7B3144B871108010613
History
DateUserTypeResult
2025-09-03Carlos PinhoCERT
PRP Certification
CERT proof power = 6
Proof certified good
2025-09-02KrieselC-PRP
E3DE4DB8546E4301
PRP proof power = 6
PRP: Verified (Factored)
Proof certified good
2017-10-30kkmrkkblmbrbkC-PRP
M1556563/280814153706489850009 : FB0426A7B3144B87
PRP: Verified
PRP without proof (not generated)
2017-10-01Oliver KruseC-PRP
M1556563/280814153706489850009 : FB0426A7B3144B87
PRP: Verified
PRP without proof (not generated)
2016-03-17alpertronNF-PM1
B1=500000, B2=15000000, E=12
2013-10-03OS1F-ECM
Factor: 280814153706489850009
2011-01-27James HeinrichNF-PM1
B1=80000, B2=1360000, E=6
2010-06-06GrunwalderGIMPNF
no factor from 2^1 to 2^63
2010-04-29Architects CubedNF
no factor from 2^60 to 2^61