is 2 640421 - 1
has 192786 decimal digits
takes 0.010 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L-unknown--unknown-
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbability
Actualunknown175000071996925008.678746.6382%8.678746.6382%
Target2440.000054.5455%110004000000.000715.9307%0.000761.7867%
Difference-440.0000-54.5455%+1739000+7199292500+8.6780+30.7075%+8.6780-15.1485%

Known prime factors (4 factors, 252.0 bits, 0.03935479% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
64042124335999824.53719
19
-1193.504e-124.364e-84.484e-8
640421622328011617281591755.78948587414499
32 × 13 × 17807 × 23321
2014-10-1417807233210.01040.00040.0008
640421210772638368408326273372374.15816455787549784308
22 × 11 × 4637 × 4813 × 16757647
2014-10-144813167576479,501.60.02020.0376
6404212325006347539288464304044325213097.553181521713649247015971060
22 × 32 × 5 × 17 × 233 × 19577 × 121789 × 106781749
2023-01-241217891067817498.331e+100.13070.2394

11 Composite Factors:
P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2014-10-14alpertronManual testing1000000300000001240129.9470.0570.0190.11431.591%
2023-01-24USAFSSUSAFSACS175000071996925003097.5538.6790.01917.3646.638%


Trial Factoring results:
No TF results for M640421


ECM factoring results:
Total ECM effort:18.833 GHz-days
Estimated T-Level:26.530
DigitsB1CompleteFacMiss
201100024.8080.000%
25500003.1824.149%
302500000.30673.637%
3510000000.02397.679%
4030000000.00299.849%


ECM Summary

B1B2factorcurvesGHz-days
5000050000002814.785
25000025000000443.746
2500004000000010010.30


Lucas-Lehmer results:
No L-L results for M640421


PRP results:
dateuseridcompidcofactorsres64PRP
2017-09-27Oliver KruseGTX-1
24335999
62232801161728159
21077263836840832627337
68A3CD2F8BB397CCno
2017-09-28Oliver KruseManual testing
24335999
62232801161728159
21077263836840832627337
68A3CD2F8BB397__no
2017-10-13Oliver KruseThreadripper68A3CD2F8BB397__no
2017-12-16ATHec2-1xf
24335999
62232801161728159
21077263836840832627337
68A3CD2F8BB397__no
2020-04-19Oliver KruseAddPrpType5
24335999
62232801161728159
21077263836840832627337
1A090F074A954A__no
2023-01-24LordJuliusWhiteBox
24335999
62232801161728159
21077263836840832627337
232500634753928846430404432521
1A090F074A954ADBno


P-1 factor-bounds graph:
B1 = 1750000, B2 = 7199692500 (P-1 stage 2)
B1 = 1000000, B2 = 30000000 (P-1 stage 2)
B1 = 1750000 (P-1 stage 1)
B1 = 1000000 (P-1 stage 1)
100
101
102
103
104
105
106
107
100
101
102
103
104
105
106
107
108
109
1010
TF factor-bounds graph:
this exponent TF target: 44
TF double-checked to: 67.7
ECM T-Level=26.53 ~= 72-bit
250
260
270
280
290
2100
Last modified: 2023-03-25T13:08:14+00:00