21987364 has 24 divisors (see below), whose sum is σ = 44509248. Its totient is φ = 9308640.

The previous prime is 21987331. The next prime is 21987373. The reversal of 21987364 is 46378912.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2407 + ... + 7054.

It is an arithmetic number, because the mean of its divisors is an integer number (1854552).

Almost surely, 2^21987364 is an apocalyptic number.

It is an amenable number.

21987364 is an abundant number, since it is smaller than the sum of its proper divisors (22521884).

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

21987364 is a wasteful number, since it uses less digits than its factorization.

21987364 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9555 (or 9553 counting only the distinct ones).

The product of its digits is 72576, while the sum is 40.

The square root of 21987364 is about 4689.0685642247. The cubic root of 21987364 is about 280.1502764748.

The spelling of 21987364 in words is "twenty-one million, nine hundred eighty-seven thousand, three hundred sixty-four".