is 2 1891861 - 1
has 569507 decimal digits
takes 0.103 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
Actual26715.706268.6567 %4000004316318161.87968.1741 %17.585871.2188 %
Target2610.162465.5738 %100008000000.00421.7259 %0.166566.1679 %
Difference+6+15.5438+3.0829 %+390000+430831816+1.8754+6.4482%+17.4193+5.0508 %

Known prime factors (1 factor, 54.6 bits, 0.00288689% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
1891861276067526516445611754.6167296189480
23 × 33 × 5 × 857 × 7883
-85778830.00239.753e-50.0001

P-1 results:
dateusercompB1B2BSstagefactordigitsbits*GHz-daysFac Prob
2022-04-12Lisander ViaeneDesktop500100500100
skipped known factor: 27606752651644561
--0.0393.952%
2022-08-29USAFSS6917th_Scty_Sq400000431631816
skipped known factor: 27606752651644561
--2.27813.458%


Trial Factoring results:
5758596061626364656667
No TF results for M1891861


ECM factoring results:
Total ECM effort:39.463 GHz-days
Estimated T-Level:25.712
DigitsB1CompleteFacMiss
201100015.0240.000%
25500001.68518.552%
302500000.14286.735%
3510000000.01099.029%


ECM Summary

B1B2factorcurvesGHz-days
500005000000422.912
50000660000020916.35
250000400000004720.21


Lucas-Lehmer results:
No L-L results for M1891861


PRP results:
dateuseridcompidcofactorsres64
2017-10-04Oliver KruseGTX-2
27606752651644561
1083A17021C8514A
2017-11-08kkmrkkblmbrbkold
27606752651644561
1083A17021C8514A


CERT results:
No CERT results for M1891861


P-1 factor-bounds graph:
B1 = 400000, B2 = 431631816 (P-1 stage 2)
B1 = 500100 (P-1 stage 1)
B1 = 400000 (P-1 stage 1)
101
102
103
104
105
106
101
102
103
104
105
106
107
108
109
TF factor-bounds graph:
this exponent TF target: 61
TF double-checked to: 67
ECM T-Level=25.71 ~= 69-bit
250
260
270
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Last modified: 2024-03-13T02:15:48+00:00