21513264 has 20 divisors (see below), whose sum is σ = 55576056. Its totient is φ = 7171072.

The previous prime is 21513259. The next prime is 21513269. The reversal of 21513264 is 46231512.

It is an interprime number because it is at equal distance from previous prime (21513259) and next prime (21513269).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21513269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 224049 + ... + 224144.

Almost surely, 2^21513264 is an apocalyptic number.

21513264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21513264 is an abundant number, since it is smaller than the sum of its proper divisors (34062792).

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

21513264 is a wasteful number, since it uses less digits than its factorization.

21513264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 448204 (or 448198 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21513264 is about 4638.2393211218. The cubic root of 21513264 is about 278.1220587830.

Adding to 21513264 its reverse (46231512), we get a palindrome (67744776).

The spelling of 21513264 in words is "twenty-one million, five hundred thirteen thousand, two hundred sixty-four".