21025625 has 10 divisors (see below), whose sum is σ = 26274402. Its totient is φ = 16820000.

The previous prime is 21025619. The next prime is 21025639. The reversal of 21025625 is 52652012.

It can be written as a sum of positive squares in 5 ways, for example, as 4897369 + 16128256 = 2213^2 + 4016^2 .

It is not a de Polignac number, because 21025625 - 2⁶ = 21025561 is a prime.

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 21025625.

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 9 ways as a sum of consecutive naturals, for example, 16196 + ... + 17445.

Almost surely, 2^21025625 is an apocalyptic number.

21025625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21025625 is a deficient number, since it is larger than the sum of its proper divisors (5248777).

21025625 is an frugal number, since it uses more digits than its factorization.

21025625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33661 (or 33646 counting only the distinct ones).

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 21025625 is about 4585.3707592735. The cubic root of 21025625 is about 276.0045901708.

Adding to 21025625 its reverse (52652012), we get a palindrome (73677637).

It can be divided in two parts, 21025 and 625, that multiplied together give a square (13140625 = 3625²).

The spelling of 21025625 in words is "twenty-one million, twenty-five thousand, six hundred twenty-five".