is 2 1921253 - 1
has 578355 decimal digits
takes 0.104 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
factored, 0 LL tests remaining
ResidueStatus
L-LB53F2200DE44E8F4double-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actual26715.465968.6567 %1000000300000000.20296.2255 %15.668970.6080 %
Target2610.159965.5738 %100008500000.00441.7618 %0.164366.1803 %
Difference+6+15.3060+3.0829 %+990000+29150000+0.1986+4.4638%+15.5046+4.4277 %

Known prime factors (1 factor, 76.8 bits, 0.00399575% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
19212531287027063822301661934792476.76833494471155602663
3 × 11164823718534221
2015-10-013111648237185342217,965.647,849,64389,369,808

P-1 results:
dateusercompB1B2BSstagefactordigitsbits*GHz-daysFac Prob
2011-09-24kurlyhex10000003000000012--0.20310.446%


Trial Factoring results:
5758596061626364656667
 BitsFactor
dateuseridcompidfromtofactorbits*digitsGHz-days
2002-12-25ANONYMOUSv4_computers212580.020
2009-06-03Architects Cubedi4l_12602610.080
2011-08-27GrunwalderGIMPManual testing212630.831
2015-05-17snme2pm1Manual testing2632641.022
2015-05-17snme2pm1Manual testing2642651.945
2015-09-02ramgeisManual testing2652663.890


ECM factoring results:
Total ECM effort:39.450 GHz-days
Estimated T-Level:25.710
DigitsB1CompleteFacMiss
201100014.9720.000%
25500001.68018.642%
302500000.14286.760%
3510000000.01099.030%


ECM Summary

B1B2factorcurvesGHz-days
10.069
500005000000322.115
50000660000021016.46
50000675000070.554
250000400000004720.25


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-01-10ANONYMOUSv4_computersB53F2200DE44E8F40.104
2015-07-10MadPooManual testingB53F2200DE44E8F40.104


PRP results:
dateuseridcompidcofactorsres64
2017-09-30alpertronManual testing
128702706382230166193479
671BB1C9394CAB6C
2017-10-20Oliver KruseThreadripper-PC
128702706382230166193479
671BB1C9394CAB6C


CERT results:
No CERT results for M1921253


P-1 factor-bounds graph:
B1 = 1000000, B2 = 30000000 (P-1 stage 2)
B1 = 1000000 (P-1 stage 1)
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1010
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1016
1017
TF factor-bounds graph:
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265
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258
this exponent TF target: 61
TF double-checked to: 67
ECM T-Level=25.71 ~= 69-bit
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Last modified: 2024-02-29T14:28:04+00:00