18221825 has 6 divisors (see below), whose sum is σ = 22595094. Its totient is φ = 14577440.

The previous prime is 18221821. The next prime is 18221837. The reversal of 18221825 is 52812281.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 2666689 + 15555136 = 1633^2 + 3944^2 .

It is not a de Polignac number, because 18221825 - 2² = 18221821 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18221821) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 364412 + ... + 364461.

It is an arithmetic number, because the mean of its divisors is an integer number (3765849).

Almost surely, 2^18221825 is an apocalyptic number.

It is an amenable number.

18221825 is a deficient number, since it is larger than the sum of its proper divisors (4373269).

18221825 is an equidigital number, since it uses as much as digits as its factorization.

18221825 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 728883 (or 728878 counting only the distinct ones).

The product of its digits is 2560, while the sum is 29.

The square root of 18221825 is about 4268.7029646018. The cubic root of 18221825 is about 263.1463136482.

The spelling of 18221825 in words is "eighteen million, two hundred twenty-one thousand, eight hundred twenty-five".