21793920 has 64 divisors (see below), whose sum is σ = 69474240. Its totient is φ = 5811200.

The previous prime is 21793909. The next prime is 21793921. The reversal of 21793920 is 2939712.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-3 number, since 3×21793920³ (a number of 23 digits) contains 333 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (21793921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3756 + ... + 7595.

It is an arithmetic number, because the mean of its divisors is an integer number (1085535).

Almost surely, 2^21793920 is an apocalyptic number.

21793920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21793920 is an abundant number, since it is smaller than the sum of its proper divisors (47680320).

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

21793920 is a wasteful number, since it uses less digits than its factorization.

21793920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11373 (or 11361 counting only the distinct ones).

The product of its (nonzero) digits is 6804, while the sum is 33.

The square root of 21793920 is about 4668.3958701036. The cubic root of 21793920 is about 279.3262713485.

The spelling of 21793920 in words is "twenty-one million, seven hundred ninety-three thousand, nine hundred twenty".