21633925 has 6 divisors (see below), whose sum is σ = 26826098. Its totient is φ = 17307120.

The previous prime is 21633919. The next prime is 21633947. The reversal of 21633925 is 52933612.

It can be written as a sum of positive squares in 3 ways, for example, as 3511876 + 18122049 = 1874^2 + 4257^2 .

It is not a de Polignac number, because 21633925 - 2³ = 21633917 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 432654 + ... + 432703.

Almost surely, 2^21633925 is an apocalyptic number.

21633925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21633925 is a deficient number, since it is larger than the sum of its proper divisors (5192173).

21633925 is an equidigital number, since it uses as much as digits as its factorization.

21633925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 865367 (or 865362 counting only the distinct ones).

The product of its digits is 9720, while the sum is 31.

The square root of 21633925 is about 4651.2283323870. The cubic root of 21633925 is about 278.6410555115.

The spelling of 21633925 in words is "twenty-one million, six hundred thirty-three thousand, nine hundred twenty-five".