21650865 has 32 divisors (see below), whose sum is σ = 36191232. Its totient is φ = 11040000.

The previous prime is 21650857. The next prime is 21650869. The reversal of 21650865 is 56805612.

It is not a de Polignac number, because 21650865 - 2³ = 21650857 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21650869) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 46735 + ... + 47195.

It is an arithmetic number, because the mean of its divisors is an integer number (1130976).

Almost surely, 2^21650865 is an apocalyptic number.

It is an amenable number.

21650865 is a deficient number, since it is larger than the sum of its proper divisors (14540367).

21650865 is a wasteful number, since it uses less digits than its factorization.

21650865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 601.

The product of its (nonzero) digits is 14400, while the sum is 33.

The square root of 21650865 is about 4653.0490003867. The cubic root of 21650865 is about 278.7137645861.

The spelling of 21650865 in words is "twenty-one million, six hundred fifty thousand, eight hundred sixty-five".