21704865 has 32 divisors (see below), whose sum is σ = 42744576. Its totient is φ = 9158400.

The previous prime is 21704857. The next prime is 21704887. The reversal of 21704865 is 56840712.

It is not a de Polignac number, because 21704865 - 2³ = 21704857 is a prime.

It is a super-2 number, since 2×21704865² = 942202329336450, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6586 + ... + 9315.

It is an arithmetic number, because the mean of its divisors is an integer number (1335768).

Almost surely, 2^21704865 is an apocalyptic number.

It is an amenable number.

21704865 is a deficient number, since it is larger than the sum of its proper divisors (21039711).

21704865 is a wasteful number, since it uses less digits than its factorization.

21704865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15929.

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21704865 is about 4658.8480335808. The cubic root of 21704865 is about 278.9452880217.

The spelling of 21704865 in words is "twenty-one million, seven hundred four thousand, eight hundred sixty-five".