21667725 has 72 divisors (see below), whose sum is σ = 41783040. Its totient is φ = 10707840.

The previous prime is 21667703. The next prime is 21667739. The reversal of 21667725 is 52776612.

It is not a de Polignac number, because 21667725 - 2²³ = 13279117 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21667725.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 274236 + ... + 274314.

It is an arithmetic number, because the mean of its divisors is an integer number (580320).

Almost surely, 2^21667725 is an apocalyptic number.

21667725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21667725 is a deficient number, since it is larger than the sum of its proper divisors (20115315).

21667725 is a wasteful number, since it uses less digits than its factorization.

21667725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 163 counting only the distinct ones).

The product of its digits is 35280, while the sum is 36.

The square root of 21667725 is about 4654.8603631044. The cubic root of 21667725 is about 278.7860926406.

The spelling of 21667725 in words is "twenty-one million, six hundred sixty-seven thousand, seven hundred twenty-five".