21207625 has 8 divisors (see below), whose sum is σ = 26467272. Its totient is φ = 16966000.

The previous prime is 21207607. The next prime is 21207631. The reversal of 21207625 is 52670212.

It can be written as a sum of positive squares in 4 ways, for example, as 1565001 + 19642624 = 1251^2 + 4432^2 .

It is not a de Polignac number, because 21207625 - 2¹⁷ = 21076553 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21207625.

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 7 ways as a sum of consecutive naturals, for example, 84706 + ... + 84955.

It is an arithmetic number, because the mean of its divisors is an integer number (3308409).

Almost surely, 2^21207625 is an apocalyptic number.

21207625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21207625 is a deficient number, since it is larger than the sum of its proper divisors (5259647).

21207625 is an equidigital number, since it uses as much as digits as its factorization.

21207625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 169676 (or 169666 counting only the distinct ones).

The product of its (nonzero) digits is 1680, while the sum is 25.

The square root of 21207625 is about 4605.1737209361. The cubic root of 21207625 is about 276.7986781500.

Adding to 21207625 its reverse (52670212), we get a palindrome (73877837).

The spelling of 21207625 in words is "twenty-one million, two hundred seven thousand, six hundred twenty-five".