is 2 2561981 - 1
has 771234 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-LEAF7D46D4EF949FEdouble-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26711.598067.1642%17500040687500.03893.5307%11.637068.3235%1.1593%
PrimeNet2590.030062.7119%110002000000.00212.6876%0.032163.7140%1.0021%
GPU722630.623065.0794%120001800000.00211.4794%0.625165.5960%0.5166%
Difference+4+10.9751+2.0848%+163000+3888750+0.0368+2.0513%+11.0119+2.7275%+2.7275%

Known prime factors (1 factor, 71.0 bits, 0.00277285% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
256198124275908708992388993692271.040473772223700964
22 × 33 × 16231 × 270271693
2015-08-1316231270271693219.091.48252.7660

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-10-23T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.293%
2003-11-08T00:00:00Team Prime Ribv4_computers15000198750---0.003--0.885%
2010-12-21T01:09:00Jocelyn LaroucheManual testing2000020000---0.002--0.316%
2011-01-03T14:36:00Jocelyn LaroucheManual testing3000030000---0.003--0.433%
2011-01-10T23:57:00Jocelyn LaroucheManual testing5000050000---0.005--0.620%
2011-04-12T22:53:00James HeinrichWHS1750004068750---0.039--3.531%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
1999-03-15T00:00:00ANONYMOUSv4_computers21259--0.030--
2022-03-11T02:05:00LordJuliusManual testing21260--0.060--
2009-01-31T19:13:00Sturle Sundegouffy.ifi260261--0.060--
2012-06-17T08:42:00Sebastian HornbostelManual testing261262--0.120--
2013-01-14T11:55:00dbaughManual testing262263--0.383--
2015-02-23T17:24:00VictordeHollanderManual testing263264--0.766--
2015-02-23T17:24:00VictordeHollanderManual testing264265--1.458--


ECM factoring results:

Old Calculation Method

Total ECM effort:1.384 GHz-days
Estimated T-Level:0.750
DigitsB1CurvesCompleteFacMiss
201100015 / 1000.15086.006%
255000015 / 2800.05494.775%

New Calculation Method

Total ECM effort:1.384 GHz-days
Estimated T-Level:0.750
DigitsB1CompleteFacMiss
20110000.48461.639%
25500000.04495.721%
302500000.00399.731%


ECM Summary

B1B2factorcurvesGHz-days
500005000000121.107
50000500000030.277


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-04-13T00:00:00PhillTv4_computersEAF7D46D4EF949FE0.178


PRP results:
dateuseridcompidcofactorsres64PRP
2017-10-15T01:56:20Oliver KruseGTX-3
2427590870899238899369
EAB4C9B8538570__no
2017-12-01T17:43:50kkmrkkblmbrbkc4.xlarge
2427590870899238899369
EAB4C9B8538570__no


P-1 factor-bounds graph:
B1 = 175000, B2 = 4068750 (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 = 198750 (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)
102
103
104
105
106
102
103
104
105
106
107
108
109
TF factor-bounds graph:
267
265
264
263
262
261
260
259
250
260
270
280
290
2100
Last modified: 2022-03-11T02:05:00+00:00