21386646 has 32 divisors (see below), whose sum is σ = 50323680. Its totient is φ = 6709248.

The previous prime is 21386639. The next prime is 21386669. The reversal of 21386646 is 64668312.

21386646 is a `hidden beast` number, since 2 + 1 + 3 + 8 + 6 + 646 = 666.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21386646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10731 + ... + 12566.

It is an arithmetic number, because the mean of its divisors is an integer number (1572615).

Almost surely, 2^21386646 is an apocalyptic number.

21386646 is an abundant number, since it is smaller than the sum of its proper divisors (28937034).

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

21386646 is a wasteful number, since it uses less digits than its factorization.

21386646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23325 (or 23319 counting only the distinct ones).

The product of its digits is 41472, while the sum is 36.

The square root of 21386646 is about 4624.5698178317. The cubic root of 21386646 is about 277.5753484215.

The spelling of 21386646 in words is "twenty-one million, three hundred eighty-six thousand, six hundred forty-six".