is 2 2851621 - 1
has 858424 decimal digits
takes 0.220 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
factored, 0 LL tests remaining
ResidueStatus
L-LBC598C3D21928C75double-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actual26820.902167.6471 %103000011967486307.41129.9637 %28.313370.8706 %
Target2630.559765.0794 %1600013000000.00961.8292 %0.569365.7181 %
Difference+5+20.3424+2.5677 %+1014000+1195448630+7.4016+8.1345%+27.7440+5.1525 %

Known prime factors (1 factor, 75.2 bits, 0.00263571% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
2851621422194078705759260347692375.1607402703211712904
23 × 178127 × 5194821119
2019-04-1117812751948211195,287.831.71659.201

P-1 results:
dateusercompB1B2BSstagefactordigitsbits*GHz-daysFac Prob
2003-11-28ANONYMOUSv4_computers2048204800--0.0010.685%
2009-07-03Carsten Kossendeymother15000157500--0.0031.550%
2010-12-22JossManual testing2000020000--0.0020.640%
2011-01-03JossManual testing3000030000--0.0040.845%
2011-01-26JossManual testing5000050000--0.0061.158%
2011-02-04markrManual testing12500027812506--0.0334.850%
2016-09-16JossManual testing16637530593756--0.0405.132%
2016-12-20JossManual testing199650199650---2.325%
2017-04-12JossManual testing33275033275006--0.0615.614%
2018-01-22JossManual testing574992574992---3.530%
2018-09-03JossManual testing85798817159766---5.034%
2018-09-05JossManual testing85798825739646--0.1175.609%
2023-04-16Kevin_9611Factor_210300001196748630--8.16714.511%


Trial Factoring results:
575859606162636465666768
 BitsFactor
dateuseridcompidfromtofactorbits*digitsGHz-days
2016-02-23Mark RoseManual testing212600.054
2009-02-13Sturle Sundegolan.ifi2602610.054
2012-01-31markroldgamer2612620.108
2013-01-10dbaughManual testing2622630.344
2015-04-21VictordeHollanderManual testing2632651.999
2016-02-16ramgeisManual testing2652662.621
2017-11-05Gordon SpenceManual testing2662675.241
2019-01-07chuenkitManual testing26726810.48


ECM factoring results:
Total ECM effort:1.713 GHz-days
Estimated T-Level:3.269
DigitsB1CompleteFacMiss
20110000.65452.004%
25500000.06094.130%
302500000.00499.619%


ECM Summary

B1B2factorcurvesGHz-days
500005000000151.504
50000500000020.209


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-06-26ANONYMOUSv4_computersBC598C3D21928C750.220
2018-09-17kkmrkkblmbrbkoldBC598C3D21928C750.215


PRP results:
dateuseridcompidcofactorsres64
2019-04-13Chang Chia-Tcheex03
42219407870575926034769
CDC353DC36FD18CB
2019-04-14kkmrkkblmbrbkc5.large
42219407870575926034769
CDC353DC36FD18CB


CERT results:
No CERT results for M2851621


P-1 factor-bounds graph:
B1 = 1030000, B2 = 1196748630 (P-1 stage 2)
B1 = 1030000 (P-1 stage 1)
B1 = 857988, B2 = 2573964 (P-1 stage 2)
B1 = 857988, B2 = 1715976 (P-1 stage 2)
B1 = 857988 (P-1 stage 1)
B1 = 574992 (P-1 stage 1)
B1 = 332750, B2 = 3327500 (P-1 stage 2)
B1 = 332750 (P-1 stage 1)
B1 = 166375, B2 = 3059375 (P-1 stage 2)
B1 = 125000, B2 = 2781250 (P-1 stage 2)
B1 = 199650 (P-1 stage 1)
B1 = 166375 (P-1 stage 1)
B1 = 125000 (P-1 stage 1)
B1 = 50000 (P-1 stage 1)
B1 = 30000 (P-1 stage 1)
B1 = 15000, B2 = 157500 (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
107
102
103
104
105
106
107
108
109
1010
TF factor-bounds graph:
268
267
266
265
263
262
261
260
this exponent TF target: 63
TF double-checked to: 67
ECM T-Level=3.27 ~= -6-bit
250
260
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280
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Last modified: 2024-03-13T02:15:48+00:00