is 2 2156521 - 1
has 649178 decimal digits
takes 0.142 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L64C838646AF32A70double-checked
PRP-unknown--unknown-

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26827.639467.6471%40000002000000001.39948.8028%29.038870.4950%2.8479%
PrimeNet2580.017862.0690%100001700000.00182.8094%0.019663.1346%1.0656%
GPU722620.284964.5161%100001600000.00171.5187%0.286665.0550%0.5389%
Difference+6+27.3545+3.1309%+3990000+199840000+1.3977+7.2840%+28.7522+5.4400%+5.4400%

Known prime factors (1 factor, 74.9 bits, 0.00347262% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
2156521349537544946016155673512374.8888104199888292675
3 × 52 × 571 × 189239927339
2020-08-165711892399273393,139.3982.961,835.9

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-03-07T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.225%
2010-11-04T10:39:00Jocelyn LaroucheManual testing1500015000---0.001--0.198%
2010-11-06T16:28:00Jocelyn LaroucheManual testing3000030000---0.003--0.353%
2010-11-07T12:40:00Jocelyn LaroucheManual testing4500045000---0.004--0.477%
2010-11-10T11:27:00Jocelyn LaroucheManual testing6000060000---0.006--0.580%
2011-01-24T02:22:00markrtiny1200002340000---0.023--2.546%
2014-10-03T21:04:00Jocelyn LaroucheManual testing149763149763---0.014--1.008%
2016-04-15T23:54:25Jocelyn LaroucheManual testing240000884343012---0.068--3.822%
2017-09-13T23:12:02Jocelyn Larouchelow 4M48000048000006---0.068--3.682%
2017-09-19T22:20:06Jocelyn Larouchelow 4M57600057600006---0.082--3.913%
2019-09-25T20:47:37mikrMSI400000020000000012---1.399--8.803%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
1999-01-29T00:00:00ANONYMOUSv4_computers21258--0.018--
2016-02-23T16:29:07Mark RoseManual testing258260--0.053--
2009-01-04T15:10:00Sturle Sundejodel.ifi260261--0.071--
2009-01-06T18:08:00Sturle Sundemorovan.ifi261262--0.142--
2013-09-08T17:50:00ramgeisManual testing262263--0.455--
2015-03-22T08:28:00VictordeHollanderManual testing263264--0.910--
2015-03-22T08:28:00VictordeHollanderManual testing264265--1.733--
2015-12-30T18:01:35ramgeisManual testing265266--3.465--
2016-11-04T03:09:03Gordon SpenceManual testing266267--6.930--
2019-05-20T13:24:29TJAOIManual testing267268--13.86--


ECM factoring results:

Old Calculation Method

Total ECM effort:9.392 GHz-days
Estimated T-Level:21.964
DigitsB1CurvesCompleteFacMiss
2011000110 / 1001.10033.103%
2550000110 / 2800.39367.465%

New Calculation Method

Total ECM effort:9.392 GHz-days
Estimated T-Level:21.964
DigitsB1CompleteFacMiss
20110003.5482.877%
25500000.32172.564%
302500000.02098.045%


ECM Summary

B1B2factorcurvesGHz-days
5000050000001089.222
50000500000020.171


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-02-14T00:00:00ANONYMOUSv4_computers64C838646AF32A700.142
2018-04-10T01:17:06kkmrkkblmbrbkold64C838646AF32A700.142


PRP results:
dateuseridcompidcofactorsres64PRP
2020-08-16T03:35:37CrypticCluecruncher
34953754494601615567351
ACB3DD4F7716A295no
2020-08-16T22:01:34atrenchDesktop
34953754494601615567351
ACB3DD4F7716A295no


P-1 factor-bounds graph:
B1 = 4000000, B2 = 200000000 (P-1 stage 2)
B1 = 4000000 (P-1 stage 1)
B1 = 576000, B2 = 5760000 (P-1 stage 2)
B1 = 480000, B2 = 4800000 (P-1 stage 2)
B1 = 240000, B2 = 8843430 (P-1 stage 2)
B1 = 576000 (P-1 stage 1)
B1 = 480000 (P-1 stage 1)
B1 = 120000, B2 = 2340000 (P-1 stage 2)
B1 = 240000 (P-1 stage 1)
B1 = 149763 (P-1 stage 1)
B1 = 120000 (P-1 stage 1)
B1 = 60000 (P-1 stage 1)
B1 = 45000 (P-1 stage 1)
B1 = 30000 (P-1 stage 1)
B1 = 15000 (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:
268
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266
265
264
263
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261
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2100
Last modified: 2020-08-16T22:01:34+00:00