21307264 has 64 divisors (see below), whose sum is σ = 47674800. Its totient is φ = 9400320.

The previous prime is 21307243. The next prime is 21307271. The reversal of 21307264 is 46270312.

It is a tau number, because it is divible by the number of its divisors (64).

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, 51892 + ... + 52300.

Almost surely, 2^21307264 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21307264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23837400).

21307264 is an abundant number, since it is smaller than the sum of its proper divisors (26367536).

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

21307264 is a wasteful number, since it uses less digits than its factorization.

21307264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 471 (or 459 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 25.

The square root of 21307264 is about 4615.9792027261. The cubic root of 21307264 is about 277.2314920282.

Adding to 21307264 its reverse (46270312), we get a palindrome (67577576).

The spelling of 21307264 in words is "twenty-one million, three hundred seven thousand, two hundred sixty-four".