21556332 has 72 divisors (see below), whose sum is σ = 62907936. Its totient is φ = 6096384.

The previous prime is 21556321. The next prime is 21556349. The reversal of 21556332 is 23365512.

21556332 is a `hidden beast` number, since 21 + 5 + 5 + 633 + 2 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21556296 and 21556305.

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, 28098 + ... + 28854.

Almost surely, 2^21556332 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 21556332, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31453968).

21556332 is an abundant number, since it is smaller than the sum of its proper divisors (41351604).

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

21556332 is a wasteful number, since it uses less digits than its factorization.

21556332 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 887 (or 882 counting only the distinct ones).

The product of its digits is 5400, while the sum is 27.

The square root of 21556332 is about 4642.8797098353. The cubic root of 21556332 is about 278.3075284940.

The spelling of 21556332 in words is "twenty-one million, five hundred fifty-six thousand, three hundred thirty-two".