21515331324 has 24 divisors (see below), whose sum is σ = 52385155200. Its totient is φ = 6859960624.

The previous prime is 21515331319. The next prime is 21515331337. The reversal of 21515331324 is 42313351512.

It is a junction number, because it is equal to n+sod(n) for n = 21515331291 and 21515331300.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 38976774 + ... + 38977325.

It is an arithmetic number, because the mean of its divisors is an integer number (2182714800).

Almost surely, 2^21515331324 is an apocalyptic number.

It is an amenable number.

21515331324 is an abundant number, since it is smaller than the sum of its proper divisors (30869823876).

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

21515331324 is a wasteful number, since it uses less digits than its factorization.

21515331324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77954129 (or 77954127 counting only the distinct ones).

The product of its digits is 10800, while the sum is 30.

Adding to 21515331324 its reverse (42313351512), we get a palindrome (63828682836).

The spelling of 21515331324 in words is "twenty-one billion, five hundred fifteen million, three hundred thirty-one thousand, three hundred twenty-four".