Those Fascinating Numbers 293
7 774 369
the fourth number which is equal to the sum of the seventh powers of its digits
added to the product of its digits (see the number 455 226).
7 860 799
the largest known prime number p such that P (p2 −1) 37 and P (p2 −1) = 37:
here p2 1 = 27 · 32 · 52 · 11 · 173 · 29 · 372 (see the number 4 801).
7 866 046
the fifth even number n such that
2n
2 (mod n) (see the number 161 038).
7 906 276
the third number 1 which is both triangular and pentagonal:
7 906 272 =
3976 · 3977
2
=
2296 · (3 · 2296 1)
2
(see the number 210).
7 989 168
the smallest Niven number n such that n +80 is also a Niven number, but with
no others in between (see the number 28 680).
8 382 464
the eighth solution of σ(n) = 2n + 2 (see the number 464).
8 388 019
the largest known regular prime (J.P. Bulher, R.E. Crandall & R.W. Sompolski
[28]).
8 489 603
the smallest number n such that τ (n) τ (n + 1) . . . τ (n + 6): here
48 20 16 12 8 6 4 (see the number 45).
8 595 928
the second n such that B(n)|B(n + 1) and B(n + 1)|B(n + 2), where
B(n) =
∑number
n
αp; the sequence of numbers satisfying this property begins
as follows: 417 162, 8 595 928, 11 506 989, 12 684 861, 20 989 800, 113 188 680,
181 665 014, . . .
Previous Page Next Page