21455625 has 20 divisors (see below), whose sum is σ = 35751056. Its totient is φ = 11442000.

The previous prime is 21455593. The next prime is 21455639. The reversal of 21455625 is 52655412.

It is not a de Polignac number, because 21455625 - 2⁵ = 21455593 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21455592 and 21455601.

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 19 ways as a sum of consecutive naturals, for example, 3847 + ... + 7596.

Almost surely, 2^21455625 is an apocalyptic number.

21455625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21455625 is a deficient number, since it is larger than the sum of its proper divisors (14295431).

21455625 is an equidigital number, since it uses as much as digits as its factorization.

21455625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11466 (or 11451 counting only the distinct ones).

The product of its digits is 12000, while the sum is 30.

The square root of 21455625 is about 4632.0216968404. The cubic root of 21455625 is about 277.8734522284.

It can be divided in two parts, 21 and 455625, that multiplied together give a triangular number (9568125 = T₄₃₇₄).

The spelling of 21455625 in words is "twenty-one million, four hundred fifty-five thousand, six hundred twenty-five".