21312552 has 32 divisors (see below), whose sum is σ = 53776800. Its totient is φ = 7038144.

The previous prime is 21312539. The next prime is 21312587. The reversal of 21312552 is 25521312.

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, 1458 + ... + 6689.

It is an arithmetic number, because the mean of its divisors is an integer number (1680525).

Almost surely, 2^21312552 is an apocalyptic number.

It is an amenable number.

21312552 is an abundant number, since it is smaller than the sum of its proper divisors (32464248).

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

21312552 is a wasteful number, since it uses less digits than its factorization.

21312552 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8265 (or 8261 counting only the distinct ones).

The product of its digits is 600, while the sum is 21.

The square root of 21312552 is about 4616.5519600672. The cubic root of 21312552 is about 277.2544244089.

Adding to 21312552 its reverse (25521312), we get a palindrome (46833864).

The spelling of 21312552 in words is "twenty-one million, three hundred twelve thousand, five hundred fifty-two".