21521374764 has 48 divisors (see below), whose sum is σ = 50396199168. Its totient is φ = 7148167488.

The previous prime is 21521374747. The next prime is 21521374789. The reversal of 21521374764 is 46747312512.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6205759 + ... + 6209225.

It is an arithmetic number, because the mean of its divisors is an integer number (1049920816).

Almost surely, 2^21521374764 is an apocalyptic number.

It is an amenable number.

21521374764 is an abundant number, since it is smaller than the sum of its proper divisors (28874824404).

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

21521374764 is a wasteful number, since it uses less digits than its factorization.

21521374764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5174 (or 5172 counting only the distinct ones).

The product of its digits is 282240, while the sum is 42.

The spelling of 21521374764 in words is "twenty-one billion, five hundred twenty-one million, three hundred seventy-four thousand, seven hundred sixty-four".