21556252 has 12 divisors (see below), whose sum is σ = 38090416. Its totient is φ = 10673280.

The previous prime is 21556247. The next prime is 21556273. The reversal of 21556252 is 25265512.

It is a self number, because there is not a number n which added to its sum of digits gives 21556252.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25749 + ... + 26572.

Almost surely, 2^21556252 is an apocalyptic number.

It is an amenable number.

21556252 is a deficient number, since it is larger than the sum of its proper divisors (16534164).

21556252 is a wasteful number, since it uses less digits than its factorization.

21556252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52428 (or 52426 counting only the distinct ones).

The product of its digits is 6000, while the sum is 28.

The square root of 21556252 is about 4642.8710944845. The cubic root of 21556252 is about 278.3071842080.

The spelling of 21556252 in words is "twenty-one million, five hundred fifty-six thousand, two hundred fifty-two".