21136312525 has 6 divisors (see below), whose sum is σ = 26209027562. Its totient is φ = 16909050000.

The previous prime is 21136312511. The next prime is 21136312531. The reversal of 21136312525 is 52521363112.

It can be written as a sum of positive squares in 3 ways, for example, as 1258884 + 21135053641 = 1122^2 + 145379^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21136312525 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 422726226 + ... + 422726275.

Almost surely, 2^21136312525 is an apocalyptic number.

21136312525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21136312525 is a deficient number, since it is larger than the sum of its proper divisors (5072715037).

21136312525 is an equidigital number, since it uses as much as digits as its factorization.

21136312525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 845452511 (or 845452506 counting only the distinct ones).

The product of its digits is 10800, while the sum is 31.

Adding to 21136312525 its reverse (52521363112), we get a palindrome (73657675637).

The spelling of 21136312525 in words is "twenty-one billion, one hundred thirty-six million, three hundred twelve thousand, five hundred twenty-five".