18008209 has 2 divisors, whose sum is σ = 18008210. Its totient is φ = 18008208.

The previous prime is 18008197. The next prime is 18008213. The reversal of 18008209 is 90280081.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17808400 + 199809 = 4220^2 + 447^2 .

It is a cyclic number.

It is not a de Polignac number, because 18008209 - 2⁹ = 18007697 is a prime.

It is not a weakly prime, because it can be changed into another prime (18008279) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9004104 + 9004105.

It is an arithmetic number, because the mean of its divisors is an integer number (9004105).

Almost surely, 2^18008209 is an apocalyptic number.

It is an amenable number.

18008209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18008209 is an equidigital number, since it uses as much as digits as its factorization.

18008209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 18008209 is about 4243.6080167706. The cubic root of 18008209 is about 262.1139734884.

The spelling of 18008209 in words is "eighteen million, eight thousand, two hundred nine".