21505864032 has 72 divisors (see below), whose sum is σ = 61171457256. Its totient is φ = 7166962176.

The previous prime is 21505864013. The next prime is 21505864057. The reversal of 21505864032 is 23046850512.

21505864032 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 5 + 8 + 640 + 3 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

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, 2454283 + ... + 2463029.

It is an arithmetic number, because the mean of its divisors is an integer number (849603573).

Almost surely, 2^21505864032 is an apocalyptic number.

It is an amenable number.

21505864032 is an abundant number, since it is smaller than the sum of its proper divisors (39665593224).

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

21505864032 is a wasteful number, since it uses less digits than its factorization.

21505864032 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17300 (or 17289 counting only the distinct ones).

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

The spelling of 21505864032 in words is "twenty-one billion, five hundred five million, eight hundred sixty-four thousand, thirty-two".