18504209 has 2 divisors, whose sum is σ = 18504210. Its totient is φ = 18504208.

The previous prime is 18504197. The next prime is 18504217. The reversal of 18504209 is 90240581.

18504209 is nontrivially palindromic in base 16.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18464209 + 40000 = 4297^2 + 200^2 .

It is a cyclic number.

It is not a de Polignac number, because 18504209 - 2⁴ = 18504193 is a prime.

It is not a weakly prime, because it can be changed into another prime (18504509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9252104 + 9252105.

It is an arithmetic number, because the mean of its divisors is an integer number (9252105).

Almost surely, 2^18504209 is an apocalyptic number.

It is an amenable number.

18504209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18504209 is an equidigital number, since it uses as much as digits as its factorization.

18504209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2880, while the sum is 29.

The square root of 18504209 is about 4301.6518920061. The cubic root of 18504209 is about 264.4986796008.

The spelling of 18504209 in words is "eighteen million, five hundred four thousand, two hundred nine".