is 2 20990471 - 1
has 6318762 decimal digits
takes 14.876 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
factored, 0 LL tests remaining
ResidueStatus
L-LF150466829AF467Cdouble-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actual2682.839663.2353%45000095000000.96915.5937%3.808765.2918%
Target2695.687763.7681%15000045000000.39773.7836%6.085365.1390%
Difference-1-2.8481-0.5328%+300000+5000000+0.5714+1.8100%-2.2766+0.1528%

Known prime factors (1 factor, 89.8 bits, 0.00042779% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
2099047110747482972292884440127179832889.79625600861867970672121
3 × 43 × 317 × 11437 × 86389 × 633629		2015-03-19863896336299,645,6750.11940.1807

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2004-02-23curtiscv4_computers205000973750---0.254--3.049%
2015-03-19riccardo ubertiPhoenix4C4500009500000122889.7960.96929.751.9385.594%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
2002-05-18Jocelyn Larouchev4_computers21257--0.001--
2002-11-24delongv4_computers21266--0.704--
2022-04-11LordJuliusManual testing266267--0.712--
2022-04-11LordJuliusManual testing267268--1.424--


ECM factoring results:
No ECM results for M20990471


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
2004-03-16curtiscv4_computersF150466829AF467C14.88
2008-08-26helicomv4_computersF150466829AF467C14.88


PRP results:
dateuseridcompidcofactorsres64PRP
2020-03-09riccardo ubertiTuareg8C
1074748297229288444012717983
D694D1A8D7C7DA0Cno
2020-06-15JaytholomewJaytholomew
1074748297229288444012717983
D694D1A8D7C7DA0Cno


P-1 factor-bounds graph:
B1 = 450000, B2 = 9500000 (P-1 stage 2)
B1 = 450000 (P-1 stage 1)
B1 = 205000, B2 = 973750 (P-1 stage 2)
B1 = 205000 (P-1 stage 1)
103
104
105
106
103
104
105
106
107
TF factor-bounds graph:
268
267
266
257
this exponent TF target: 69
TF double-checked to: 67.8
250
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290
Last modified: 2023-04-26T21:34:10+00:00