404 Jean-Marie De Koninck
2756 838(2756 839
1)
the
32nd
even perfect number, a 455 663 digit number.
2859 432(2859 433 1)
the 33rd even perfect number, a 517 430 digit number.
2221
+ 1
the
22nd
Fermat number, a 631 306 digit number; it is composite and its smallest
prime factor, discovered by Wrathall in 1963, is
4 485 296 422 913 = 534 689 ·
223
+ 1
(see the number 70 525 124 609).
21 257 786(21 257 787 1)
the 34th even perfect number, a 757 263 digit number.
21 398 268(21 398 269
1)
the
35th
even perfect number, a 841 842 digit number.
22 976 221
1
the 36th Mersenne prime, a 895 932 digit number (see the number 2 976 221).
23 021 377 1
the
37th
Mersenne prime, a 909 525 digit number (see the number 3 021 377).
2222
+ 1
the
23rd
Fermat number, a 1 262 612 digit number; it was proven to be compos-
ite by Crandall, Doenias, Norrie and Young in 1995 (see the number 70 525 124 609).
22 976 220(22 976 221 1)
the
36th
even perfect number, a 1 791 864 digit number.
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