21056533456 has 20 divisors (see below), whose sum is σ = 46625181472. Its totient is φ = 9024228576.

The previous prime is 21056533441. The next prime is 21056533471. The reversal of 21056533456 is 65433565012.

It is an interprime number because it is at equal distance from previous prime (21056533441) and next prime (21056533471).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 94002270 + ... + 94002493.

Almost surely, 2^21056533456 is an apocalyptic number.

It is an amenable number.

21056533456 is an abundant number, since it is smaller than the sum of its proper divisors (25568648016).

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

21056533456 is a wasteful number, since it uses less digits than its factorization.

21056533456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 188004778 (or 188004772 counting only the distinct ones).

The product of its (nonzero) digits is 324000, while the sum is 40.

The spelling of 21056533456 in words is "twenty-one billion, fifty-six million, five hundred thirty-three thousand, four hundred fifty-six".