21404664 has 48 divisors (see below), whose sum is σ = 58237920. Its totient is φ = 7102080.

The previous prime is 21404653. The next prime is 21404681. The reversal of 21404664 is 46640412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18964 + ... + 20060.

It is an arithmetic number, because the mean of its divisors is an integer number (1213290).

Almost surely, 2^21404664 is an apocalyptic number.

21404664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21404664 is an abundant number, since it is smaller than the sum of its proper divisors (36833256).

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

21404664 is a wasteful number, since it uses less digits than its factorization.

21404664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1380 (or 1373 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 27.

The square root of 21404664 is about 4626.5174807840. The cubic root of 21404664 is about 277.6532778727.

The spelling of 21404664 in words is "twenty-one million, four hundred four thousand, six hundred sixty-four".