18540209 has 2 divisors, whose sum is σ = 18540210. Its totient is φ = 18540208.

The previous prime is 18540199. The next prime is 18540227. The reversal of 18540209 is 90204581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17875984 + 664225 = 4228^2 + 815^2 .

It is a cyclic number.

It is not a de Polignac number, because 18540209 - 2¹² = 18536113 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18540229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9270104 + 9270105.

It is an arithmetic number, because the mean of its divisors is an integer number (9270105).

Almost surely, 2^18540209 is an apocalyptic number.

It is an amenable number.

18540209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18540209 is an equidigital number, since it uses as much as digits as its factorization.

18540209 is an odious number, because the sum of its binary digits is odd.

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

The square root of 18540209 is about 4305.8342977871. The cubic root of 18540209 is about 264.6700961712.

The spelling of 18540209 in words is "eighteen million, five hundred forty thousand, two hundred nine".