21312704 has 56 divisors (see below), whose sum is σ = 48877728. Its totient is φ = 9031680.

The previous prime is 21312677. The next prime is 21312721. The reversal of 21312704 is 40721312.

It is a tau number, because it is divible by the number of its divisors (56).

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, 50414 + ... + 50834.

Almost surely, 2^21312704 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 21312704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24438864).

21312704 is an abundant number, since it is smaller than the sum of its proper divisors (27565024).

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

21312704 is a wasteful number, since it uses less digits than its factorization.

21312704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 553 (or 543 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21312704 is about 4616.5684225407. The cubic root of 21312704 is about 277.2550835287.

The spelling of 21312704 in words is "twenty-one million, three hundred twelve thousand, seven hundred four".