21973872 has 20 divisors (see below), whose sum is σ = 56765960. Its totient is φ = 7324608.

The previous prime is 21973871. The next prime is 21973873. The reversal of 21973872 is 27837912.

It is an interprime number because it is at equal distance from previous prime (21973871) and next prime (21973873).

It is a self number, because there is not a number n which added to its sum of digits gives 21973872.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21973871) 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 3 ways as a sum of consecutive naturals, for example, 228847 + ... + 228942.

It is an arithmetic number, because the mean of its divisors is an integer number (2838298).

Almost surely, 2^21973872 is an apocalyptic number.

It is an amenable number.

21973872 is an abundant number, since it is smaller than the sum of its proper divisors (34792088).

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

21973872 is a wasteful number, since it uses less digits than its factorization.

21973872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 457800 (or 457794 counting only the distinct ones).

The product of its digits is 42336, while the sum is 39.

The square root of 21973872 is about 4687.6296782062. The cubic root of 21973872 is about 280.0929623296.

The spelling of 21973872 in words is "twenty-one million, nine hundred seventy-three thousand, eight hundred seventy-two".