Those Fascinating Numbers 377
2 346 318 816 620 308
the number of 17 digit prime numbers.
2 360 712 083 917 682
the third number n such that
n2
+ 1 is powerful: here
2 360 712 083 917
6822
+ 1 =
55
·
612
·
30012
·
2306865012
(see the number 682).
2 623 557 157 654 233
the number of prime numbers
1017.
3 904 305 912 313 344 (= 549)
the smallest number n 1 whose sum of digits is equal to
9

n: the only
other numbers n 1 satisfying this property are 45 848 500 718 449 031 and
150 094 635 296 999 121.
5 056 584 744 960 000
the value of 1! · 2! · . . . · 8!.
5 315 654 681 981 355
the
16th
horse number (see the number 13).
6 992 962 672 132 095 (= 3 · 5 · 17 · 353 · 929 · 83 623 937)
the largest known number n for which φ(n)|(n + 1) (see the number 65 535).
8 314 460 009 856 000
the smallest number n = [d1, d2, . . . , dr] such that (d1 + 7) · (d2 + 7) · . . . · (dr +
7) = n; Patrick Letendre established, for 1 t 9, the following solutions of
(d1 + t) · (d2 + t) · . . . · (dr + t) = n:
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