21386764 has 24 divisors (see below), whose sum is σ = 42872480. Its totient is φ = 9144576.

The previous prime is 21386759. The next prime is 21386773. The reversal of 21386764 is 46768312.

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, 20692 + ... + 21700.

Almost surely, 2^21386764 is an apocalyptic number.

It is an amenable number.

21386764 is an abundant number, since it is smaller than the sum of its proper divisors (21485716).

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

21386764 is a wasteful number, since it uses less digits than its factorization.

21386764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1777 (or 1775 counting only the distinct ones).

The product of its digits is 48384, while the sum is 37.

The square root of 21386764 is about 4624.5825757575. The cubic root of 21386764 is about 277.5758589243.

The spelling of 21386764 in words is "twenty-one million, three hundred eighty-six thousand, seven hundred sixty-four".