21304864 has 24 divisors (see below), whose sum is σ = 47936448. Its totient is φ = 9130560.

The previous prime is 21304847. The next prime is 21304867. The reversal of 21304864 is 46840312.

It is a Harshad number since it is a multiple of its sum of digits (28).

It is not an unprimeable number, because it can be changed into a prime (21304867) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47332 + ... + 47779.

It is an arithmetic number, because the mean of its divisors is an integer number (1997352).

Almost surely, 2^21304864 is an apocalyptic number.

It is an amenable number.

21304864 is an abundant number, since it is smaller than the sum of its proper divisors (26631584).

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

21304864 is an equidigital number, since it uses as much as digits as its factorization.

21304864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95128 (or 95120 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 28.

The square root of 21304864 is about 4615.7192288960. The cubic root of 21304864 is about 277.2210827368.

The spelling of 21304864 in words is "twenty-one million, three hundred four thousand, eight hundred sixty-four".