21765868 has 12 divisors (see below), whose sum is σ = 40095160. Its totient is φ = 10310112.

The previous prime is 21765859. The next prime is 21765893. The reversal of 21765868 is 86856712.

It is a hoax number, since the sum of its digits (43) 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, 143121 + ... + 143272.

Almost surely, 2^21765868 is an apocalyptic number.

It is an amenable number.

21765868 is a deficient number, since it is larger than the sum of its proper divisors (18329292).

21765868 is a wasteful number, since it uses less digits than its factorization.

21765868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286416 (or 286414 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 21765868 is about 4665.3904445394. The cubic root of 21765868 is about 279.2063751442.

The spelling of 21765868 in words is "twenty-one million, seven hundred sixty-five thousand, eight hundred sixty-eight".