21535872 has 64 divisors (see below), whose sum is σ = 60588000. Its totient is φ = 6754304.

The previous prime is 21535859. The next prime is 21535897. The reversal of 21535872 is 27853512.

It is a tau number, because it is divible by the number of its divisors (64).

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, 4879 + ... + 8177.

Almost surely, 2^21535872 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 21535872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30294000).

21535872 is an abundant number, since it is smaller than the sum of its proper divisors (39052128).

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

21535872 is a wasteful number, since it uses less digits than its factorization.

21535872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3333 (or 3321 counting only the distinct ones).

The product of its digits is 16800, while the sum is 33.

The square root of 21535872 is about 4640.6758128531. The cubic root of 21535872 is about 278.2194495866.

The spelling of 21535872 in words is "twenty-one million, five hundred thirty-five thousand, eight hundred seventy-two".