21556244 has 24 divisors (see below), whose sum is σ = 40286400. Its totient is φ = 10067904.

The previous prime is 21556231. The next prime is 21556247. The reversal of 21556244 is 44265512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21556247) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1232 + ... + 6680.

It is an arithmetic number, because the mean of its divisors is an integer number (1678600).

Almost surely, 2^21556244 is an apocalyptic number.

It is an amenable number.

21556244 is a deficient number, since it is larger than the sum of its proper divisors (18730156).

21556244 is a wasteful number, since it uses less digits than its factorization.

21556244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5519 (or 5517 counting only the distinct ones).

The product of its digits is 9600, while the sum is 29.

The square root of 21556244 is about 4642.8702329486. The cubic root of 21556244 is about 278.3071497793.

The spelling of 21556244 in words is "twenty-one million, five hundred fifty-six thousand, two hundred forty-four".