21933904 has 40 divisors (see below), whose sum is σ = 46693440. Its totient is φ = 9934848.

The previous prime is 21933887. The next prime is 21933907. The reversal of 21933904 is 40933912.

It is a super-2 number, since 2×21933904² = 962192289362432, which contains 22 as substring.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21933907) 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, 5424 + ... + 8560.

It is an arithmetic number, because the mean of its divisors is an integer number (1167336).

Almost surely, 2^21933904 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21933904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23346720).

21933904 is an abundant number, since it is smaller than the sum of its proper divisors (24759536).

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

21933904 is a wasteful number, since it uses less digits than its factorization.

21933904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3187 (or 3181 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 31.

The square root of 21933904 is about 4683.3646025053. The cubic root of 21933904 is about 279.9230400735.

The spelling of 21933904 in words is "twenty-one million, nine hundred thirty-three thousand, nine hundred four".