is 2 8221 - 1
has 2475 decimal digits
takes 0.000 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
Actualunknown1000000010000000000.009433.9785%0.009433.9785%
Target2440.000368.1818%500100000.00001.1897%0.000368.5604%
Difference-44-0.0003-68.1818%+9999500+999990000+0.0094+32.7887%+0.0091-34.5819%

Known prime factors (5 factors, 218.4 bits, 2.65645899% known):
Remaining cofactor is not a probable-prime

P-1GHz-days
exponentfactordigitsbits*kdate foundmin B1min B2min. TFmin. P-1normal P-1
8221920753619.81256
23 × 7
-888.599e-121.179e-92.400e-9
82219667897723.205588
22 × 3 × 72
-49491.532e-107.223e-91.470e-8
822118480809824.1401124
22 × 281
-42813.380e-102.814e-94.208e-9
8221664135739274326471755.8824039263710463
3 × 1346421236821
-313464212368210.834410.81420.198
8221504351329908140879449460961432995.3483067457303905491299412851
47 × 691 × 2993681 × 3095621 × 10191763
-3095621101917631.840e+120.00050.0009

26 Composite Factors:
P-1 results:
 GHz-DaysworthFactor
probability
dateuseridcompidb1b2estagefactordigitsbits*spentsaved
2021-08-25H Michaelson100000001000000000-
skipped known factor: 920753
skipped known factor: 9667897
skipped known factor: 18480809
skipped known factor: 50435132990814087944946096143
--0.009--33.978%
2021-08-27Seth_TrManual testing400000000400000000-
skipped known factor: 920753
skipped known factor: 9667897
skipped known factor: 18480809
skipped known factor: 50435132990814087944946096143
--0.059--29.909%


Trial Factoring results:
No TF results for M8221


ECM factoring results:
Total ECM effort:1,311.834 GHz-days
Estimated T-Level:45.778
DigitsB1CompleteFacMiss
20110003,177.8000.000%
2550000890.3980.000%
30250000232.9370.000%
35100000047.2030.000%
4030000008.0500.032%
45110000001.19330.330%
50440000000.15685.589%
551100000000.01898.190%
602600000000.00299.813%


ECM Summary

B1B2factorcurvesGHz-days
30000003000000003,88924.75
11000000365788846624,8001,287


Lucas-Lehmer results:
No L-L results for M8221


PRP results:
dateuseridcompidcofactorsres64PRP
2017-09-21Oliver KruseOliver-PCE3FBBDFA850BC9__?
2017-09-21Oliver KruseManual testingE3FBBDFA850BC9__?
2017-10-02kkmrkkblmbrbkManual testing
920753
9667897
18480809
66413573927432647
50435132990814087944946096143
E3FBBDFA850BC9__no
2017-12-07ATHManual testing
920753
9667897
18480809
66413573927432647
50435132990814087944946096143
E3FBBDFA850BC9__no
2020-04-17Oliver KruseManual testing
920753
9667897
18480809
66413573927432647
50435132990814087944946096143
859897F075C263__no


P-1 factor-bounds graph:
B1 = 400000000 (P-1 stage 1)
B1 = 10000000, B2 = 1000000000 (P-1 stage 2)
B1 = 10000000 (P-1 stage 1)
100
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106
107
108
109
100
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102
103
104
105
106
107
108
109
1010
1011
1012
1013
TF factor-bounds graph:
this exponent TF target: 44
TF double-checked to: 67.7
ECM T-Level=45.78 ~= 135-bit
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Last modified: 2023-03-23T17:39:31+00:00