is 2 2081851 - 1
has 626700 decimal digits
takes 0.137 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L2364C0F989737D51double-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26957.346569.5652%25000001250000000.87467.2671%58.221171.7770%2.2117%
PrimeNet2580.018463.7931%90001600000.00162.6734%0.020164.7611%0.9680%
GPU722620.295166.1290%90001400000.00151.3991%0.296666.6029%0.4739%
Difference+7+57.0514+3.4362%+2491000+124860000+0.8731+5.8680%+57.9245+5.1740%+5.1740%

Known prime factors:
No known factors for M2081851

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-02-27T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.179%
2009-07-26T11:34:00harleeP4_260020000260000---0.003--0.751%
2010-12-28T02:15:00Jocelyn LaroucheManual testing3000030000---0.003--0.297%
2011-01-07T22:30:00Jocelyn LaroucheManual testing5000050000---0.005--0.435%
2011-01-24T13:33:00James HeinrichQ66001350002936250---0.027--2.431%
2016-07-07T00:37:27Jocelyn LaroucheManual testing182413587250012---0.047--2.999%
2016-11-04T12:39:35Jocelyn Larouchelow 4M218895218895---0.021--1.075%
2016-11-07T03:11:22Jocelyn Larouchelow 4M262674262674---0.025--1.181%
2016-11-11T16:54:52Jocelyn Larouchelow 4M315208315208---0.030--1.294%
2017-04-02T14:54:12mikrMSI250000012500000012---0.875--7.267%
2017-05-13T16:00:17Jocelyn Larouchelow 4M39024939024906---0.055--3.072%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
1999-01-10T00:00:00ANONYMOUSv4_computers21258--0.018--
2016-02-23T16:29:05Mark RoseManual testing258260--0.055--
2009-01-03T04:08:00Sturle Sundekinner.ifi260261--0.074--
2012-03-17T18:47:00Sebastian HornbostelManual testing261262--0.148--
2013-09-02T08:36:00ramgeisManual testing262263--0.472--
2015-03-31T15:56:00VictordeHollanderManual testing263264--0.943--
2015-03-31T15:56:00VictordeHollanderManual testing264265--1.795--
2015-11-05T09:47:18ramgeisManual testing265266--3.589--
2016-09-14T10:22:38Gordon SpenceManual testing266267--7.179--
2019-04-01T03:15:22chuenkitManual testing267268--14.36--
2021-08-26T09:33:35TJAOIManual testing268269--28.72--


ECM factoring results:

Old Calculation Method

Total ECM effort:17.596 GHz-days
Estimated T-Level:23.696
DigitsB1CurvesCompleteFacMiss
2011000207 / 1002.07012.488%
2550000207 / 2800.73947.682%

New Calculation Method

Total ECM effort:17.596 GHz-days
Estimated T-Level:23.696
DigitsB1CompleteFacMiss
20110007.9620.035%
25500000.73747.871%
302500000.04695.460%
3510000000.00299.783%


ECM Summary

B1B2factorcurvesGHz-days
50000500000020717.60


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-03-01T00:00:00ANONYMOUSv4_computers2364C0F989737D510.137
2017-06-09T09:47:19kkmrkkblmbrbkc4.large2364C0F989737D510.137


PRP results:
No PRP results for M2081851


P-1 factor-bounds graph:
B1 = 2500000, B2 = 125000000 (P-1 stage 2)
B1 = 2500000 (P-1 stage 1)
B1 = 390249, B2 = 3902490 (P-1 stage 2)
B1 = 182413, B2 = 5872500 (P-1 stage 2)
B1 = 390249 (P-1 stage 1)
B1 = 315208 (P-1 stage 1)
B1 = 135000, B2 = 2936250 (P-1 stage 2)
B1 = 262674 (P-1 stage 1)
B1 = 218895 (P-1 stage 1)
B1 = 182413 (P-1 stage 1)
B1 = 135000 (P-1 stage 1)
B1 = 50000 (P-1 stage 1)
B1 = 20000, B2 = 260000 (P-1 stage 2)
B1 = 30000 (P-1 stage 1)
B1 = 20000 (P-1 stage 1)
B1 = 2048, B2 = 204800 (P-1 stage 2)
B1 = 2048 (P-1 stage 1)
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TF factor-bounds graph:
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Last modified: 2022-02-23T18:11:22+00:00