Those Fascinating Numbers 263
523 776 (= 29 · 3 · 11 · 31)
the third tri-perfect number (see the number 120).
524 160 (= 27 · 32 · 5 · 7 · 13)
the smallest solution of
σ(n)
n
=
17
4
.
524 287 (= 219 1)
the seventh Mersenne prime.
529 620
the seventh number n such that φ(n)σ(n) is a fourth power: here
φ(529620)σ(529620) =
6724
(see the number 170).
531 434
the second solution of σ(n + 7) = σ(n) + 7 (see the number 74).
540 857
the fifth composite number n such that 2n−2 1 (mod n); see the number
20 737.
542 603
the smallest prime number p such that p + 80 is prime and such that each
number between p and p + 80 is composite (see the number 139).
545 835
the eighth horse number (see the number 13).
548 834
the only number 1 which can be written as the sum of the sixth powers of
its digits: 548 834 =
56
+
46
+
86
+
86
+
36
+
46.
548 856
the eighth number n such that σ(φ(n)) = n (see the number 744).
Previous Page Next Page