21904764 has 36 divisors (see below), whose sum is σ = 59457384. Its totient is φ = 6258336.

The previous prime is 21904747. The next prime is 21904781. The reversal of 21904764 is 46740912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21904747) and next prime (21904781).

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, 18039 + ... + 19214.

It is an arithmetic number, because the mean of its divisors is an integer number (1651594).

Almost surely, 2^21904764 is an apocalyptic number.

It is an amenable number.

21904764 is an abundant number, since it is smaller than the sum of its proper divisors (37552620).

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

21904764 is a wasteful number, since it uses less digits than its factorization.

21904764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37274 (or 37265 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 33.

The square root of 21904764 is about 4680.2525572879. The cubic root of 21904764 is about 279.7990224441.

The spelling of 21904764 in words is "twenty-one million, nine hundred four thousand, seven hundred sixty-four".