is 2 2828887 - 1
has 851580 decimal digits
takes 0.218 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L2A8866F3FE864390double-checked
PRPF34DA0BE76FE5BC1verified PRP

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26821.070167.6471%50000002000000001.74989.1671%22.819970.6129%2.9658%
PrimeNet2590.027162.7119%120002400000.00272.9325%0.029963.8053%1.0935%
GPU722630.564265.0794%160002600000.00331.8264%0.567565.7172%0.6378%
Difference+5+20.5059+2.5677%+4984000+199740000+1.7465+7.3407%+22.2524+4.8957%+4.8957%

Known prime factors (1 factor, 88.8 bits, 0.00314065% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
28288875561188136896502229825670072788.84698292864594741716969
419753 × 234168343275073
2021-03-2141975323416834327507337,262,9561,428,8142,668,627

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-11-28T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.244%
2016-09-19T01:31:06Jocelyn Larouchelow 4M12000033000006---0.033--2.866%
2016-09-21T12:09:20Jocelyn Larouchelow 4M1200003630000---0.035--2.927%
2016-09-22T12:02:48Jocelyn Larouchelow 4M1200003993000---0.037--2.988%
2016-12-16T01:22:15Jocelyn Larouchelow 4M172800172800---0.019--1.142%
2016-12-24T02:28:29Jocelyn Larouchelow 4M207360207360---0.023--1.255%
2017-02-25T21:08:04Jocelyn Larouchelow 4M29859829859806---0.050--3.228%
2017-10-07T21:35:20Jocelyn Larouchelow 4M59719659719606---0.100--4.096%
2019-11-10T16:24:56masserManual testing30000003000000012---0.501--6.484%
2020-01-24T15:13:26masserManual testing500000020000000012---1.750--9.167%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
2016-02-23T16:29:22Mark RoseManual testing21260--0.054--
2009-02-14T00:23:00Sturle Sundegigi.ifi260261--0.054--
2012-02-13T23:34:00markroldgamer261262--0.109--
2013-01-10T10:23:00dbaughManual testing262263--0.347--
2015-04-21T09:19:00VictordeHollanderManual testing263264--0.694--
2015-04-21T09:19:00VictordeHollanderManual testing264265--1.321--
2016-02-13T14:46:56ramgeisManual testing265266--2.642--
2017-10-28T16:39:40Gordon SpenceManual testing266267--5.283--
2019-01-04T01:17:00chuenkitManual testing267268--10.57--


ECM factoring results:

Old Calculation Method

Total ECM effort:8.355 GHz-days
Estimated T-Level:3.950
DigitsB1CurvesCompleteFacMiss
201100079 / 1000.79045.204%
255000079 / 2800.28275.379%

New Calculation Method

Total ECM effort:8.355 GHz-days
Estimated T-Level:3.950
DigitsB1CompleteFacMiss
20110002.5647.700%
25500000.23279.290%
302500000.01498.580%


ECM Summary

B1B2factorcurvesGHz-days
500005000000656.783
50000500000070.730
50000675000070.841


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-12-23T00:00:00akohlerv4_computers2A8866F3FE8643900.218
2018-09-09T19:35:25kkmrkkblmbrbkold2A8866F3FE8643900.218


PRP results:
dateuseridcompidcofactorsres64PRP
2021-03-21T15:28:36XZTN4640G1
556118813689650222982567007
F34DA0BE76FE5BC1no


P-1 factor-bounds graph:
B1 = 5000000, B2 = 200000000 (P-1 stage 2)
B1 = 5000000 (P-1 stage 1)
B1 = 3000000, B2 = 30000000 (P-1 stage 2)
B1 = 3000000 (P-1 stage 1)
B1 = 597196, B2 = 5971960 (P-1 stage 2)
B1 = 597196 (P-1 stage 1)
B1 = 298598, B2 = 2985980 (P-1 stage 2)
B1 = 120000, B2 = 3993000 (P-1 stage 2)
B1 = 120000, B2 = 3630000 (P-1 stage 2)
B1 = 298598 (P-1 stage 1)
B1 = 120000, B2 = 3300000 (P-1 stage 2)
B1 = 207360 (P-1 stage 1)
B1 = 172800 (P-1 stage 1)
B1 = 120000 (P-1 stage 1)
B1 = 2048, B2 = 204800 (P-1 stage 2)
B1 = 2048 (P-1 stage 1)
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TF factor-bounds graph:
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Last modified: 2021-03-21T15:28:36+00:00