21425872 has 40 divisors (see below), whose sum is σ = 44997120. Its totient is φ = 9824640.

The previous prime is 21425851. The next prime is 21425881. The reversal of 21425872 is 27852412.

It is a happy number.

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, 49497 + ... + 49927.

It is an arithmetic number, because the mean of its divisors is an integer number (1124928).

Almost surely, 2^21425872 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 21425872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22498560).

21425872 is an abundant number, since it is smaller than the sum of its proper divisors (23571248).

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

21425872 is a wasteful number, since it uses less digits than its factorization.

21425872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 691 (or 685 counting only the distinct ones).

The product of its digits is 8960, while the sum is 31.

The square root of 21425872 is about 4628.8089180695. The cubic root of 21425872 is about 277.7449483454.

The spelling of 21425872 in words is "twenty-one million, four hundred twenty-five thousand, eight hundred seventy-two".