21431604 has 24 divisors (see below), whose sum is σ = 50083488. Its totient is φ = 7132960.

The previous prime is 21431593. The next prime is 21431623. The reversal of 21431604 is 40613412.

It is a congruent number.

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, 12274 + ... + 13910.

It is an arithmetic number, because the mean of its divisors is an integer number (2086812).

Almost surely, 2^21431604 is an apocalyptic number.

It is an amenable number.

21431604 is an abundant number, since it is smaller than the sum of its proper divisors (28651884).

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

21431604 is a wasteful number, since it uses less digits than its factorization.

21431604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2735 (or 2733 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 21431604 is about 4629.4280424260. The cubic root of 21431604 is about 277.7697142311.

The spelling of 21431604 in words is "twenty-one million, four hundred thirty-one thousand, six hundred four".