382 Jean-Marie De Koninck
711 813 411 914 121 216
the smallest insolite number containing the maximum possible number of dis-
tinct digits, namely the digits 1, 2, 3, 4, 6, 7, 8 and 9 (see the number 111).
999 999 999 999 999 989
the largest 18 digit prime number.
1 000 000 000 000 000 003
the smallest 19 digit prime number.
1 111 111 111 111 111 111
the second prime number of the form 11 . . . 1 (see the number 19).
1 610 006 506 595 061 125 (=
53
·
172
·
612
·
1094412)
the second powerful number n such that n 1 is a perfect square, namely
1 268 860
3182
(see the number 682).
1 986 761 935 284 574 233
the number of 20 digit prime numbers.
2 206 550 475 483 180 841
the smallest sixth power which can be written as the sum of seven sixth powers:
2 206 550 475 483 180 841 =
11416
=
746+2346+4026+4746+7026+8946+10776.
2 220 819 602 560 918 840
the number of prime numbers
1020
(an estimate due to Marc Del´eglise).
2 305 843 008 139 952 128 (= 230(231 1))
the eight perfect number.
2 305 843 009 213 693 951
the ninth Mersenne prime, namely
261
1.
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