21831656 has 96 divisors (see below), whose sum is σ = 53434080. Its totient is φ = 8265600.

The previous prime is 21831647. The next prime is 21831661. The reversal of 21831656 is 65613812.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 262991 + ... + 263073.

It is an arithmetic number, because the mean of its divisors is an integer number (556605).

Almost surely, 2^21831656 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 21831656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26717040).

21831656 is an abundant number, since it is smaller than the sum of its proper divisors (31602424).

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

21831656 is a wasteful number, since it uses less digits than its factorization.

21831656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 175 (or 164 counting only the distinct ones).

The product of its digits is 8640, while the sum is 32.

The square root of 21831656 is about 4672.4357673488. The cubic root of 21831656 is about 279.4873954653.

The spelling of 21831656 in words is "twenty-one million, eight hundred thirty-one thousand, six hundred fifty-six".