21557168 has 20 divisors (see below), whose sum is σ = 41864880. Its totient is φ = 10753344.

The previous prime is 21557143. The next prime is 21557177. The reversal of 21557168 is 86175512.

It is a super-2 number, since 2×21557168² = 929422984360448, which contains 22 as substring.

It is a hoax number, since the sum of its digits (35) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6821 + ... + 9467.

It is an arithmetic number, because the mean of its divisors is an integer number (2093244).

Almost surely, 2^21557168 is an apocalyptic number.

It is an amenable number.

21557168 is a deficient number, since it is larger than the sum of its proper divisors (20307712).

21557168 is a wasteful number, since it uses less digits than its factorization.

21557168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3164 (or 3158 counting only the distinct ones).

The product of its digits is 16800, while the sum is 35.

The square root of 21557168 is about 4642.9697392940. The cubic root of 21557168 is about 278.3111262317.

The spelling of 21557168 in words is "twenty-one million, five hundred fifty-seven thousand, one hundred sixty-eight".