is 2 12871841 - 1
has 3874811 decimal digits
takes 5.258 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
factored, 0 LL tests remaining
ResidueStatus
L-L08F8BE76A0CE65FEdouble-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actual2672.308464.1791 %40000042845985014.050110.0014 %16.358667.7617 %
Target2684.630664.7059 %90000120000000.43763.1642 %5.068365.8227 %
Difference-1-2.3222-0.5268 %+310000+416459850+13.6125+6.8372%+11.2903+1.9390 %

Known prime factors (1 factor, 88.8 bits, 0.00068973% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
128718415317476334006504547940442312788.78120655461538122264515
5 × 839 × 21727 × 59119 × 3833329
2015-07-245911938333299,544,9920.15680.2310

P-1 results:
dateusercompB1B2BSstagefactordigitsbits*GHz-daysFac Prob
2001-08-31ANONYMOUSv4_computers200000200000--0.1181.586%
2015-07-24ThaRiet-Ubuntu2788.7810.3620.000%
2022-04-19nordisweet16_30.8b14400000400000--0.2372.163%
2022-05-20nordisweet16_30.8b14400000428459850
skipped known factor: 531747633400650454794044231
--16.479.194%


Trial Factoring results:
575859606162636465666768
 BitsFactor
dateuseridcompidfromtofactorbits*digitsGHz-days
2000-04-12lalerav4_computers212620.024
2000-04-19ANONYMOUSv4_computers212640.153
2013-06-02lycornManual testing2642650.290
2014-04-27NesowaManual testing2652660.581
2015-04-11ThaManual testing2662671.161


ECM factoring results:
No ECM results for M12871841


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
2001-12-22ANONYMOUSv4_computers08F8BE76A0CE65FE5.258
2004-10-03Bobbi and the Straysv4_computers08F8BE76A0CE65FE5.258
2006-02-01Bobbi and the Straysv4_computers08F8BE76A0CE65FE5.258


PRP results:
dateuseridcompidcofactorsres64
2022-05-18XZTM900Tiny3
531747633400650454794044231
7EE9E6FD2594558F


CERT results:
dateuseridcompid
2022-05-18Gufesadragon


P-1 factor-bounds graph:
B1 = 400000, B2 = 428459850 (P-1 stage 2)
B1 = 400000 (P-1 stage 1)
B1 = 200000 (P-1 stage 1)
103
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105
106
103
104
105
106
107
108
109
TF factor-bounds graph:
267
266
265
264
262
this exponent TF target: 68
TF double-checked to: 67
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Last modified: 2024-03-13T02:15:48+00:00