21938520 has 32 divisors (see below), whose sum is σ = 65815920. Its totient is φ = 5850240.

The previous prime is 21938491. The next prime is 21938533. The reversal of 21938520 is 2583912.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 91291 + ... + 91530.

Almost surely, 2^21938520 is an apocalyptic number.

21938520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21938520 is an abundant number, since it is smaller than the sum of its proper divisors (43877400).

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

21938520 is a wasteful number, since it uses less digits than its factorization.

21938520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 182835 (or 182831 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 30.

The square root of 21938520 is about 4683.8573846777. The cubic root of 21938520 is about 279.9426753395.

The spelling of 21938520 in words is "twenty-one million, nine hundred thirty-eight thousand, five hundred twenty".