21405251466 has 24 divisors (see below), whose sum is σ = 46391436000. Its totient is φ = 7133023656.

The previous prime is 21405251447. The next prime is 21405251471. The reversal of 21405251466 is 66415250412.

21405251466 is a `hidden beast` number, since 2 + 140 + 5 + 2 + 51 + 466 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 21405251466.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 106950 + ... + 232913.

It is an arithmetic number, because the mean of its divisors is an integer number (1932976500).

Almost surely, 2^21405251466 is an apocalyptic number.

21405251466 is an abundant number, since it is smaller than the sum of its proper divisors (24986184534).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405251466 is a wasteful number, since it uses less digits than its factorization.

21405251466 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343370 (or 343367 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 36.

The spelling of 21405251466 in words is "twenty-one billion, four hundred five million, two hundred fifty-one thousand, four hundred sixty-six".