21372764 has 24 divisors (see below), whose sum is σ = 44126208. Its totient is φ = 8863920.

The previous prime is 21372761. The next prime is 21372787. The reversal of 21372764 is 46727312.

21372764 = 1631² + 1632² + ... + 1638².

It is a Smith number, since the sum of its digits (32) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21372764.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11444 + ... + 13179.

It is an arithmetic number, because the mean of its divisors is an integer number (1838592).

Almost surely, 2^21372764 is an apocalyptic number.

It is an amenable number.

21372764 is an abundant number, since it is smaller than the sum of its proper divisors (22753444).

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

21372764 is a wasteful number, since it uses less digits than its factorization.

21372764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24665 (or 24663 counting only the distinct ones).

The product of its digits is 14112, while the sum is 32.

The square root of 21372764 is about 4623.0686778373. The cubic root of 21372764 is about 277.5152776806.

The spelling of 21372764 in words is "twenty-one million, three hundred seventy-two thousand, seven hundred sixty-four".