21765872 has 10 divisors (see below), whose sum is σ = 42171408. Its totient is φ = 10882928.

The previous prime is 21765859. The next prime is 21765893. The reversal of 21765872 is 27856712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 680168 + ... + 680199.

Almost surely, 2^21765872 is an apocalyptic number.

It is an amenable number.

21765872 is a deficient number, since it is larger than the sum of its proper divisors (20405536).

21765872 is a wasteful number, since it uses less digits than its factorization.

21765872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1360375 (or 1360369 counting only the distinct ones).

The product of its digits is 47040, while the sum is 38.

The square root of 21765872 is about 4665.3908732281. The cubic root of 21765872 is about 279.2063922478.

The spelling of 21765872 in words is "twenty-one million, seven hundred sixty-five thousand, eight hundred seventy-two".