21113556 has 12 divisors (see below), whose sum is σ = 49264992. Its totient is φ = 7037848.

The previous prime is 21113549. The next prime is 21113581. The reversal of 21113556 is 65531112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 879720 + ... + 879743.

It is an arithmetic number, because the mean of its divisors is an integer number (4105416).

Almost surely, 2^21113556 is an apocalyptic number.

It is an amenable number.

21113556 is an abundant number, since it is smaller than the sum of its proper divisors (28151436).

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

21113556 is a wasteful number, since it uses less digits than its factorization.

21113556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1759470 (or 1759468 counting only the distinct ones).

The product of its digits is 900, while the sum is 24.

The square root of 21113556 is about 4594.9489659843. The cubic root of 21113556 is about 276.3888134826.

Adding to 21113556 its reverse (65531112), we get a palindrome (86644668).

The spelling of 21113556 in words is "twenty-one million, one hundred thirteen thousand, five hundred fifty-six".