21567725 has 12 divisors (see below), whose sum is σ = 27367296. Its totient is φ = 16852080.

The previous prime is 21567703. The next prime is 21567739. The reversal of 21567725 is 52776512.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21567725 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8957 + ... + 11106.

It is an arithmetic number, because the mean of its divisors is an integer number (2280608).

Almost surely, 2^21567725 is an apocalyptic number.

21567725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21567725 is a deficient number, since it is larger than the sum of its proper divisors (5799571).

21567725 is a wasteful number, since it uses less digits than its factorization.

21567725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20116 (or 20111 counting only the distinct ones).

The product of its digits is 29400, while the sum is 35.

The square root of 21567725 is about 4644.1064802608. The cubic root of 21567725 is about 278.3565504276.

The spelling of 21567725 in words is "twenty-one million, five hundred sixty-seven thousand, seven hundred twenty-five".