21056505156 has 36 divisors (see below), whose sum is σ = 54358641792. Its totient is φ = 6869497584.

The previous prime is 21056505143. The next prime is 21056505163. The reversal of 21056505156 is 65150565012.

It is a tau number, because it is divible by the number of its divisors (36).

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

It is a self number, because there is not a number n which added to its sum of digits gives 21056505156.

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, 6220680 + ... + 6224063.

It is an arithmetic number, because the mean of its divisors is an integer number (1509962272).

Almost surely, 2^21056505156 is an apocalyptic number.

It is an amenable number.

21056505156 is an abundant number, since it is smaller than the sum of its proper divisors (33302136636).

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

21056505156 is a wasteful number, since it uses less digits than its factorization.

21056505156 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12444800 (or 12444795 counting only the distinct ones).

The product of its (nonzero) digits is 45000, while the sum is 36.

The spelling of 21056505156 in words is "twenty-one billion, fifty-six million, five hundred five thousand, one hundred fifty-six".