is 2 2780621 - 1
has 837051 decimal digits
takes 0.215 GHz-days to do one PRP test
Last-known PrimeNet details:
Exponent is not assigned to anyone
0 primality tests remaining
ResidueStatus
L-L97B0FDD77A0B8912double-checked
PRPD7EF90A786662F36verified PRP

 Trial FactoringP-1 FactoringCombined
LimitGHz-daysProbabilityB1B2GHz-daysProbabilityGHz-daysProbabilityProb over default TF
Actual26821.435867.6471%2700000840000000.79847.6852%22.234370.1334%2.4864%
PrimeNet2590.027662.7119%120002200000.00262.8582%0.030263.7776%1.0658%
GPU722630.574065.0794%150002400000.00311.7475%0.577065.6896%0.6102%
Difference+5+20.8618+2.5677%+2685000+83760000+0.7954+5.9377%+21.6572+4.4438%+4.4438%

Known prime factors (1 factor, 78.5 bits, 0.00282243% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
27806214218669998467608094575592478.48175858414333841399
13 × 61 × 228257 × 419089199
2021-05-2722825741908919925,8232.58134.7760

P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2003-11-17T00:00:00ANONYMOUSv4_computers2048204800---0.001--0.242%
2010-11-10T22:07:00Jocelyn LaroucheManual testing1500015000---0.002--0.210%
2010-11-26T17:21:00markrtiny1100002392500---0.026--2.615%
2016-08-31T02:37:24Jocelyn Larouchelow4M14000047850006---0.044--3.187%
2016-12-21T00:33:42Jocelyn Larouchelow 4M201600201600---0.023--1.233%
2017-02-25T21:07:56Jocelyn Larouchelow 4M29030429030406---0.048--3.188%
2017-03-20T01:06:58Jocelyn Larouchelow 4M34836434836406---0.058--3.405%
2017-04-02T08:12:24mikrMSI27000008400000012---0.798--7.685%


Trial Factoring results:
 BitsFactorGHz-Daysworth
dateuseridcompidfromtofactorbits*digitsspentsaved
2016-02-23T16:29:21Mark RoseManual testing21260--0.055--
2009-01-28T03:11:00Sturle Sundegicy.ifi260261--0.055--
2012-03-16T22:38:00Grant McCrackenhome261262--0.110--
2013-01-10T10:21:00dbaughManual testing262263--0.353--
2015-04-21T09:20:00VictordeHollanderManual testing263264--0.706--
2015-04-21T09:20:00VictordeHollanderManual testing264265--1.344--
2015-12-20T08:25:37omylistManual testing265266--2.687--
2017-10-16T21:21:13Gordon SpenceManual testing266267--5.375--
2019-02-24T11:40:40chuenkitManual testing267268--10.75--


ECM factoring results:

Old Calculation Method

Total ECM effort:9.684 GHz-days
Estimated T-Level:4.600
DigitsB1CurvesCompleteFacMiss
201100092 / 1000.92039.668%
255000092 / 2800.32971.953%

New Calculation Method

Total ECM effort:9.684 GHz-days
Estimated T-Level:4.600
DigitsB1CompleteFacMiss
20110002.9835.062%
25500000.27076.341%
302500000.01798.351%


ECM Summary

B1B2factorcurvesGHz-days
500005000000828.533
50000500000030.312
50000675000070.839


Lucas-Lehmer results:
dateuseridcompidres64spent (GHz-days)
1999-04-23T00:00:00ANONYMOUSv4_computers97B0FDD77A0B89120.215
2018-08-25T16:03:43kkmrkkblmbrbkold97B0FDD77A0B89120.215


PRP results:
dateuseridcompidcofactorsres64PRP
2021-05-28T19:35:17M89093871
421866999846760809457559
D7EF90A786662F36no


P-1 factor-bounds graph:
B1 = 2700000, B2 = 84000000 (P-1 stage 2)
B1 = 2700000 (P-1 stage 1)
B1 = 348364, B2 = 3483640 (P-1 stage 2)
B1 = 290304, B2 = 2903040 (P-1 stage 2)
B1 = 140000, B2 = 4785000 (P-1 stage 2)
B1 = 348364 (P-1 stage 1)
B1 = 290304 (P-1 stage 1)
B1 = 110000, B2 = 2392500 (P-1 stage 2)
B1 = 201600 (P-1 stage 1)
B1 = 140000 (P-1 stage 1)
B1 = 110000 (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:
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Last modified: 2021-05-28T19:35:17+00:00