21075864 has 32 divisors (see below), whose sum is σ = 55464000. Its totient is φ = 6655392.

The previous prime is 21075863. The next prime is 21075871. The reversal of 21075864 is 46857012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21075863) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22654 + ... + 23565.

It is an arithmetic number, because the mean of its divisors is an integer number (1733250).

Almost surely, 2^21075864 is an apocalyptic number.

21075864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21075864 is an abundant number, since it is smaller than the sum of its proper divisors (34388136).

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

21075864 is a wasteful number, since it uses less digits than its factorization.

21075864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46247 (or 46243 counting only the distinct ones).

The product of its (nonzero) digits is 13440, while the sum is 33.

The square root of 21075864 is about 4590.8456737294. The cubic root of 21075864 is about 276.2242453963.

The spelling of 21075864 in words is "twenty-one million, seventy-five thousand, eight hundred sixty-four".