21533264 has 40 divisors (see below), whose sum is σ = 43256160. Its totient is φ = 10378368.

The previous prime is 21533263. The next prime is 21533269. The reversal of 21533264 is 46233512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533263) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56627 + ... + 57005.

It is an arithmetic number, because the mean of its divisors is an integer number (1081404).

Almost surely, 2^21533264 is an apocalyptic number.

It is an amenable number.

21533264 is an abundant number, since it is smaller than the sum of its proper divisors (21722896).

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

21533264 is a wasteful number, since it uses less digits than its factorization.

21533264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 507 (or 501 counting only the distinct ones).

The product of its digits is 4320, while the sum is 26.

The square root of 21533264 is about 4640.3948107893. The cubic root of 21533264 is about 278.2082183161.

Adding to 21533264 its reverse (46233512), we get a palindrome (67766776).

The spelling of 21533264 in words is "twenty-one million, five hundred thirty-three thousand, two hundred sixty-four".