is 2 2567821 - 1
has 772992 decimal digits
takes 0.178 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L14F921551EC20868double-checked
PRP08DD319EF2187E52verified PRP

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26823.212267.6471%32000001120000000.91808.0784%24.130270.2606%2.6136%
PrimeNet2590.029962.7119%110002000000.00212.6887%0.032063.7144%1.0026%
GPU722630.621565.0794%120001800000.00211.4801%0.623765.5962%0.5169%
Difference+5+22.5907+2.5677%+3188000+111820000+0.9159+6.5983%+23.5066+4.6644%+4.6644%

Known prime factors (1 factor, 89.0 bits, 0.00346611% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
25678216204857421814441500476219532789.004120819508482375553056
25 × 3 × 23 × 4679 × 11694588649483
2020-12-2346791169458864948391,688,01664,081119,685

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-10-23T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.237%
2003-11-08T00:00:00Team Prime Ribv4_computers15000202500---0.003--0.761%
2010-12-21T01:09:00Jocelyn LaroucheManual testing2000020000---0.002--0.265%
2011-01-03T22:20:00Jocelyn LaroucheManual testing3000030000---0.003--0.367%
2011-01-10T23:57:00Jocelyn LaroucheManual testing5000050000---0.005--0.532%
2011-04-15T21:20:00James HeinrichWHS1750004112500---0.039--3.173%
2016-05-29T07:42:25mikrMSI320000011200000012---0.918--8.078%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
1999-03-15T00:00:00Stephan Gruppv4_computers21259--0.030--
2016-02-23T16:29:16Mark RoseManual testing259260--0.030--
2009-01-27T23:50:00Sturle Sundedittersdorf.ifi260261--0.060--
2012-06-17T16:42:00Sebastian HornbostelManual testing261262--0.120--
2013-01-23T08:30:00dbaughManual testing262263--0.382--
2015-02-23T17:24:00VictordeHollanderManual testing263264--0.765--
2015-02-23T17:24:00VictordeHollanderManual testing264265--1.455--
2015-11-08T21:03:02ramgeisManual testing265266--2.910--
2017-08-13T10:39:20Gordon SpenceManual testing266267--5.820--
2019-05-13T13:38:12TJAOIManual testing267268--11.64--


ECM factoring results:

Old Calculation Method

Total ECM effort:8.220 GHz-days
Estimated T-Level:4.250
DigitsB1CurvesCompleteFacMiss
201100085 / 1000.85042.559%
255000085 / 2800.30473.778%

New Calculation Method

Total ECM effort:8.220 GHz-days
Estimated T-Level:4.250
DigitsB1CompleteFacMiss
20110002.7766.226%
25500000.25077.888%
302500000.01598.476%


ECM Summary

B1B2factorcurvesGHz-days
500005000070.375
500005000000817.477
50000500000040.369


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-04-13T00:00:00Stephan Gruppv4_computers14F921551EC208680.178
2018-06-16T02:13:39kkmrkkblmbrbkold14F921551EC208680.178


PRP results:
dateuseridcompidcofactorsres64PRP
2020-12-23T12:37:38SRJ2877LTOS
620485742181444150047621953
08DD319EF2187E52no


P-1 factor-bounds graph:
B1 = 3200000, B2 = 112000000 (P-1 stage 2)
B1 = 3200000 (P-1 stage 1)
B1 = 175000, B2 = 4112500 (P-1 stage 2)
B1 = 175000 (P-1 stage 1)
B1 = 50000 (P-1 stage 1)
B1 = 30000 (P-1 stage 1)
B1 = 15000, B2 = 202500 (P-1 stage 2)
B1 = 20000 (P-1 stage 1)
B1 = 15000 (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: 2020-12-23T12:37:38+00:00