21564412131 has 16 divisors (see below), whose sum is σ = 29046636288. Its totient is φ = 14229324000.

The previous prime is 21564412097. The next prime is 21564412139. The reversal of 21564412131 is 13121446512.

It is not a de Polignac number, because 21564412131 - 2⁷ = 21564412003 is a prime.

It is a super-2 number, since 2×21564412131² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21564412139) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1102620 + ... + 1122006.

It is an arithmetic number, because the mean of its divisors is an integer number (1815414768).

Almost surely, 2^21564412131 is an apocalyptic number.

21564412131 is a deficient number, since it is larger than the sum of its proper divisors (7482224157).

21564412131 is a wasteful number, since it uses less digits than its factorization.

21564412131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23162.

The product of its digits is 5760, while the sum is 30.

Adding to 21564412131 its reverse (13121446512), we get a palindrome (34685858643).

The spelling of 21564412131 in words is "twenty-one billion, five hundred sixty-four million, four hundred twelve thousand, one hundred thirty-one".