21438656 has 28 divisors (see below), whose sum is σ = 44013120. Its totient is φ = 10348800.

The previous prime is 21438647. The next prime is 21438673. The reversal of 21438656 is 65683412.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3920 + ... + 7631.

Almost surely, 2^21438656 is an apocalyptic number.

It is an amenable number.

21438656 is an abundant number, since it is smaller than the sum of its proper divisors (22574464).

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

21438656 is a wasteful number, since it uses less digits than its factorization.

21438656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11592 (or 11582 counting only the distinct ones).

The product of its digits is 34560, while the sum is 35.

The square root of 21438656 is about 4630.1896289461. The cubic root of 21438656 is about 277.8001772989.

The spelling of 21438656 in words is "twenty-one million, four hundred thirty-eight thousand, six hundred fifty-six".