21732920 has 32 divisors (see below), whose sum is σ = 53345520. Its totient is φ = 7902720.

The previous prime is 21732917. The next prime is 21732943. The reversal of 21732920 is 2923712.

It is a self number, because there is not a number n which added to its sum of digits gives 21732920.

It is a congruent number.

It is an unprimeable number.

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, 24257 + ... + 25136.

Almost surely, 2^21732920 is an apocalyptic number.

21732920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21732920 is an abundant number, since it is smaller than the sum of its proper divisors (31612600).

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

21732920 is a wasteful number, since it uses less digits than its factorization.

21732920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49415 (or 49411 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21732920 is about 4661.8579986954. The cubic root of 21732920 is about 279.0654214676.

The spelling of 21732920 in words is "twenty-one million, seven hundred thirty-two thousand, nine hundred twenty".