21611625 has 32 divisors (see below), whose sum is σ = 41104128. Its totient is φ = 9878400.

The previous prime is 21611621. The next prime is 21611669. The reversal of 21611625 is 52611612.

It is not a de Polignac number, because 21611625 - 2² = 21611621 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21611595 and 21611604.

It is not an unprimeable number, because it can be changed into a prime (21611621) by changing a digit.

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 31 ways as a sum of consecutive naturals, for example, 1492 + ... + 6741.

It is an arithmetic number, because the mean of its divisors is an integer number (1284504).

Almost surely, 2^21611625 is an apocalyptic number.

21611625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21611625 is a deficient number, since it is larger than the sum of its proper divisors (19492503).

21611625 is an equidigital number, since it uses as much as digits as its factorization.

21611625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8258 (or 8248 counting only the distinct ones).

The product of its digits is 720, while the sum is 24.

The square root of 21611625 is about 4648.8304980930. The cubic root of 21611625 is about 278.5452826029.

The spelling of 21611625 in words is "twenty-one million, six hundred eleven thousand, six hundred twenty-five".