Those Fascinating Numbers 273
947 519
the fifth solution of σ2(n) = σ2(n + 2) (see the number 1 079).
965 177
the smallest number n which allows the sum
m≤n
1
σ(m)
to exceed 10 (see the
number 129).
968 760
the smallest Niven number n such that n +70 is also a Niven number, but with
no others in between (see the number 28 680).
974 849
the second prime factor of the Fermat number F11 =
2211
+ 1 (see the number
319 489).
987 631
the largest prime number made up of exactly six distinct digits (see the number
9 871).
990 361
the smallest number n requiring 13 iterations of the σI (n) function in order to
reach 1 (see the number 193).
990 409
the fourth composite number n such that 2n−4 1 (mod n); see the number
40 369.
999 983
the largest six digit prime number.
1 000 003
the smallest seven digit prime number.
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