21165772 has 12 divisors (see below), whose sum is σ = 38989720. Its totient is φ = 10025856.

The previous prime is 21165757. The next prime is 21165787. The reversal of 21165772 is 27756112.

It is an interprime number because it is at equal distance from previous prime (21165757) and next prime (21165787).

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, 139173 + ... + 139324.

Almost surely, 2^21165772 is an apocalyptic number.

It is an amenable number.

21165772 is a deficient number, since it is larger than the sum of its proper divisors (17823948).

21165772 is a wasteful number, since it uses less digits than its factorization.

21165772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 278520 (or 278518 counting only the distinct ones).

The product of its digits is 5880, while the sum is 31.

The square root of 21165772 is about 4600.6273485254. The cubic root of 21165772 is about 276.6164719184.

The spelling of 21165772 in words is "twenty-one million, one hundred sixty-five thousand, seven hundred seventy-two".