21312354515 has 16 divisors (see below), whose sum is σ = 25981344480. Its totient is φ = 16780815360.

The previous prime is 21312354467. The next prime is 21312354527. The reversal of 21312354515 is 51545321312.

It is a de Polignac number, because none of the positive numbers 2^k-21312354515 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33605 + ... + 209174.

It is an arithmetic number, because the mean of its divisors is an integer number (1623834030).

Almost surely, 2^21312354515 is an apocalyptic number.

21312354515 is a deficient number, since it is larger than the sum of its proper divisors (4668989965).

21312354515 is a wasteful number, since it uses less digits than its factorization.

21312354515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243062.

The product of its digits is 18000, while the sum is 32.

Adding to 21312354515 its reverse (51545321312), we get a palindrome (72857675827).

The spelling of 21312354515 in words is "twenty-one billion, three hundred twelve million, three hundred fifty-four thousand, five hundred fifteen".