21712625 has 16 divisors (see below), whose sum is σ = 29562624. Its totient is φ = 15790000.

The previous prime is 21712567. The next prime is 21712631. The reversal of 21712625 is 52621712.

It is a de Polignac number, because none of the positive numbers 2^k-21712625 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21712594 and 21712603.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6521 + ... + 9270.

It is an arithmetic number, because the mean of its divisors is an integer number (1847664).

Almost surely, 2^21712625 is an apocalyptic number.

21712625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21712625 is a deficient number, since it is larger than the sum of its proper divisors (7849999).

21712625 is a wasteful number, since it uses less digits than its factorization.

21712625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15817 (or 15807 counting only the distinct ones).

The product of its digits is 1680, while the sum is 26.

The square root of 21712625 is about 4659.6807830580. The cubic root of 21712625 is about 278.9785272289.

The spelling of 21712625 in words is "twenty-one million, seven hundred twelve thousand, six hundred twenty-five".