21156233580 has 36 divisors (see below), whose sum is σ = 64173909072. Its totient is φ = 5641662240.

The previous prime is 21156233513. The next prime is 21156233603. The reversal of 21156233580 is 8533265112.

21156233580 is a `hidden beast` number, since 2 + 1 + 1 + 56 + 23 + 3 + 580 = 666.

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 an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 58767136 + ... + 58767495.

Almost surely, 2^21156233580 is an apocalyptic number.

21156233580 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21156233580 is an abundant number, since it is smaller than the sum of its proper divisors (43017675492).

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

21156233580 is a wasteful number, since it uses less digits than its factorization.

21156233580 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117534646 (or 117534641 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

Adding to 21156233580 its reverse (8533265112), we get a palindrome (29689498692).

The spelling of 21156233580 in words is "twenty-one billion, one hundred fifty-six million, two hundred thirty-three thousand, five hundred eighty".