18391225 has 6 divisors (see below), whose sum is σ = 22805150. Its totient is φ = 14712960.

The previous prime is 18391213. The next prime is 18391271. The reversal of 18391225 is 52219381.

It can be written as a sum of positive squares in 3 ways, for example, as 5257849 + 13133376 = 2293^2 + 3624^2 .

It is not a de Polignac number, because 18391225 - 2¹³ = 18383033 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 367800 + ... + 367849.

Almost surely, 2^18391225 is an apocalyptic number.

It is an amenable number.

18391225 is a deficient number, since it is larger than the sum of its proper divisors (4413925).

18391225 is an equidigital number, since it uses as much as digits as its factorization.

18391225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 735659 (or 735654 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 18391225 is about 4288.4991547160. The cubic root of 18391225 is about 263.9592501000.

The spelling of 18391225 in words is "eighteen million, three hundred ninety-one thousand, two hundred twenty-five".