21664300 has 36 divisors (see below), whose sum is σ = 53729200. Its totient is φ = 7427520.

The previous prime is 21664297. The next prime is 21664327. The reversal of 21664300 is 346612.

It is a plaindrome in base 11.

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, 14775 + ... + 16174.

Almost surely, 2^21664300 is an apocalyptic number.

21664300 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21664300 is an abundant number, since it is smaller than the sum of its proper divisors (32064900).

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

21664300 is a wasteful number, since it uses less digits than its factorization.

21664300 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30970 (or 30963 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 22.

The square root of 21664300 is about 4654.4924535335. The cubic root of 21664300 is about 278.7714027015.

It can be divided in two parts, 216 and 64300, that added together give a square (64516 = 254²).

The spelling of 21664300 in words is "twenty-one million, six hundred sixty-four thousand, three hundred".