21432656 has 40 divisors (see below), whose sum is σ = 48996864. Its totient is φ = 8887680.

The previous prime is 21432629. The next prime is 21432661. The reversal of 21432656 is 65623412.

It is a congruent number.

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, 386 + ... + 6558.

Almost surely, 2^21432656 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 21432656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24498432).

21432656 is an abundant number, since it is smaller than the sum of its proper divisors (27564208).

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

21432656 is a wasteful number, since it uses less digits than its factorization.

21432656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6219 (or 6213 counting only the distinct ones).

The product of its digits is 8640, while the sum is 29.

The square root of 21432656 is about 4629.5416619791. The cubic root of 21432656 is about 277.7742590606.

The spelling of 21432656 in words is "twenty-one million, four hundred thirty-two thousand, six hundred fifty-six".