is 2 2554247 - 1
has 768905 decimal digits
takes 0.177 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L19698C2F85D7DF7Adouble-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26823.335667.6471%32000001120000000.91808.0742%24.253670.2593%2.6122%
PrimeNet2590.030162.7119%110002000000.00212.6861%0.032263.7135%1.0016%
GPU722630.624865.0794%120001800000.00211.4785%0.627065.5957%0.5163%
Difference+5+22.7107+2.5677%+3188000+111820000+0.9159+6.5957%+23.6266+4.6636%+4.6636%

Known prime factors (1 factor, 82.2 bits, 0.00321821% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
255424755591429296571793568276472582.2011088215612988324809
4937 × 220420419888257
2020-07-044937220420419888257721,1981,207,8002,255,834

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-10-23T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.236%
2003-11-08T00:00:00Team Prime Ribv4_computers15000198750---0.003--0.756%
2010-12-19T21:44:00Jocelyn LaroucheManual testing2000020000---0.002--0.265%
2011-01-03T14:35:00Jocelyn LaroucheManual testing3000030000---0.003--0.367%
2011-01-09T14:30:00Jocelyn LaroucheManual testing5000050000---0.005--0.531%
2011-04-09T16:12:00James HeinrichWHS1750004068750---0.039--3.163%
2016-03-29T17:07:18mikrMSI320000011200000012---0.918--8.074%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
1999-03-15T00:00:00ANONYMOUSv4_computers21259--0.030--
2016-02-23T16:29:16Mark RoseManual testing259260--0.030--
2009-01-30T16:00:00Sturle Sundegorky.ifi260261--0.060--
2012-06-16T17:43:00Sebastian HornbostelManual testing261262--0.120--
2013-01-23T08:30:00dbaughManual testing262263--0.384--
2015-02-23T17:24:00VictordeHollanderManual testing263264--0.769--
2015-02-23T17:24:00VictordeHollanderManual testing264265--1.463--
2015-11-04T20:25:08omylistManual testing265266--2.926--
2017-08-10T07:53:54Gordon SpenceManual testing266267--5.851--
2019-06-10T09:46:16TJAOIManual testing267268--11.70--


ECM factoring results:

Old Calculation Method

Total ECM effort:3.874 GHz-days
Estimated T-Level:2.100
DigitsB1CurvesCompleteFacMiss
201100042 / 1000.42065.566%
255000042 / 2800.15086.048%

New Calculation Method

Total ECM effort:3.874 GHz-days
Estimated T-Level:2.100
DigitsB1CompleteFacMiss
20110001.35525.799%
25500000.12288.475%
302500000.00899.249%


ECM Summary

B1B2factorcurvesGHz-days
500005000000393.597
50000500000030.277


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-04-02T00:00:00Dry Creek Photov4_computers19698C2F85D7DF7A0.177
2018-06-12T12:12:01kkmrkkblmbrbkold19698C2F85D7DF7A0.177


PRP results:
dateuseridcompidcofactorsres64PRP
2020-07-04T17:02:16CrypticCluecruncher
5559142929657179356827647
87589DDC750627A2no
2020-07-05T18:05:03marssystemssystem11
5559142929657179356827647
87589DDC750627A2no


P-1 factor-bounds graph:
B1 = 3200000, B2 = 112000000 (P-1 stage 2)
B1 = 3200000 (P-1 stage 1)
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)
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TF factor-bounds graph:
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Last modified: 2020-07-05T18:05:03+00:00