21686464 has 14 divisors (see below), whose sum is σ = 43034204. Its totient is φ = 10843200.

The previous prime is 21686449. The next prime is 21686471. The reversal of 21686464 is 46468612.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 169362 + ... + 169489.

Almost surely, 2^21686464 is an apocalyptic number.

It is an amenable number.

21686464 is a deficient number, since it is larger than the sum of its proper divisors (21347740).

21686464 is an equidigital number, since it uses as much as digits as its factorization.

21686464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 338863 (or 338853 counting only the distinct ones).

The product of its digits is 55296, while the sum is 37.

The square root of 21686464 is about 4656.8727704330. The cubic root of 21686464 is about 278.8664374437.

The spelling of 21686464 in words is "twenty-one million, six hundred eighty-six thousand, four hundred sixty-four".