21855125 has 16 divisors (see below), whose sum is σ = 28220400. Its totient is φ = 16878400.

The previous prime is 21855121. The next prime is 21855131. The reversal of 21855125 is 52155812.

It can be written as a sum of positive squares in 8 ways, for example, as 2292196 + 19562929 = 1514^2 + 4423^2 .

It is not a de Polignac number, because 21855125 - 2² = 21855121 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21855121) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 611 + ... + 6639.

It is an arithmetic number, because the mean of its divisors is an integer number (1763775).

Almost surely, 2^21855125 is an apocalyptic number.

21855125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21855125 is a deficient number, since it is larger than the sum of its proper divisors (6365275).

21855125 is an equidigital number, since it uses as much as digits as its factorization.

21855125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6073 (or 6063 counting only the distinct ones).

The product of its digits is 4000, while the sum is 29.

The square root of 21855125 is about 4674.9465237583. The cubic root of 21855125 is about 279.5875091210.

The spelling of 21855125 in words is "twenty-one million, eight hundred fifty-five thousand, one hundred twenty-five".