21164404 has 12 divisors (see below), whose sum is σ = 38987200. Its totient is φ = 10025208.

The previous prime is 21164401. The next prime is 21164431. The reversal of 21164404 is 40446112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21164401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139164 + ... + 139315.

Almost surely, 2^21164404 is an apocalyptic number.

It is an amenable number.

21164404 is a deficient number, since it is larger than the sum of its proper divisors (17822796).

21164404 is a wasteful number, since it uses less digits than its factorization.

21164404 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278502 (or 278500 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 22.

The square root of 21164404 is about 4600.4786707472. The cubic root of 21164404 is about 276.6105123045.

The spelling of 21164404 in words is "twenty-one million, one hundred sixty-four thousand, four hundred four".