18840209 has 2 divisors, whose sum is σ = 18840210. Its totient is φ = 18840208.

The previous prime is 18840179. The next prime is 18840221. The reversal of 18840209 is 90204881.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11833600 + 7006609 = 3440^2 + 2647^2 .

It is a cyclic number.

It is not a de Polignac number, because 18840209 - 2¹² = 18836113 is a prime.

It is not a weakly prime, because it can be changed into another prime (18840509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9420104 + 9420105.

It is an arithmetic number, because the mean of its divisors is an integer number (9420105).

Almost surely, 2^18840209 is an apocalyptic number.

It is an amenable number.

18840209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18840209 is an equidigital number, since it uses as much as digits as its factorization.

18840209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 18840209 is about 4340.5309583045. The cubic root of 18840209 is about 266.0900113716.

The spelling of 18840209 in words is "eighteen million, eight hundred forty thousand, two hundred nine".