21531392 has 36 divisors (see below), whose sum is σ = 43340976. Its totient is φ = 10675200.

The previous prime is 21531379. The next prime is 21531439. The reversal of 21531392 is 29313512.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38378 + ... + 38934.

It is an arithmetic number, because the mean of its divisors is an integer number (1203916).

Almost surely, 2^21531392 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 21531392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21670488).

21531392 is an abundant number, since it is smaller than the sum of its proper divisors (21809584).

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

21531392 is an equidigital number, since it uses as much as digits as its factorization.

21531392 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 724 (or 710 counting only the distinct ones).

The product of its digits is 1620, while the sum is 26.

The square root of 21531392 is about 4640.1930994302. The cubic root of 21531392 is about 278.2001560474.

The spelling of 21531392 in words is "twenty-one million, five hundred thirty-one thousand, three hundred ninety-two".