21162556 has 12 divisors (see below), whose sum is σ = 37154992. Its totient is φ = 10546848.

The previous prime is 21162551. The next prime is 21162613. The reversal of 21162556 is 65526112.

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21162551) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7200 + ... + 9703.

Almost surely, 2^21162556 is an apocalyptic number.

It is an amenable number.

21162556 is a deficient number, since it is larger than the sum of its proper divisors (15992436).

21162556 is a wasteful number, since it uses less digits than its factorization.

21162556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17220 (or 17218 counting only the distinct ones).

The product of its digits is 3600, while the sum is 28.

The square root of 21162556 is about 4600.2778176975. The cubic root of 21162556 is about 276.6024611902.

Adding to 21162556 its reverse (65526112), we get a palindrome (86688668).

The spelling of 21162556 in words is "twenty-one million, one hundred sixty-two thousand, five hundred fifty-six".