21523872 has 48 divisors (see below), whose sum is σ = 56941920. Its totient is φ = 7118592.

The previous prime is 21523847. The next prime is 21523891. The reversal of 21523872 is 27832512.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12538 + ... + 14150.

It is an arithmetic number, because the mean of its divisors is an integer number (1186290).

Almost surely, 2^21523872 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 21523872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28470960).

21523872 is an abundant number, since it is smaller than the sum of its proper divisors (35418048).

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

21523872 is a wasteful number, since it uses less digits than its factorization.

21523872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1765 (or 1757 counting only the distinct ones).

The product of its digits is 6720, while the sum is 30.

The square root of 21523872 is about 4639.3827175606. The cubic root of 21523872 is about 278.1677644464.

The spelling of 21523872 in words is "twenty-one million, five hundred twenty-three thousand, eight hundred seventy-two".