18347209 has 2 divisors, whose sum is σ = 18347210. Its totient is φ = 18347208.

The previous prime is 18347191. The next prime is 18347221. The reversal of 18347209 is 90274381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18020025 + 327184 = 4245^2 + 572^2 .

It is an emirp because it is prime and its reverse (90274381) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18347209 - 2¹³ = 18339017 is a prime.

It is not a weakly prime, because it can be changed into another prime (18347809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9173604 + 9173605.

It is an arithmetic number, because the mean of its divisors is an integer number (9173605).

Almost surely, 2^18347209 is an apocalyptic number.

It is an amenable number.

18347209 is a deficient number, since it is larger than the sum of its proper divisors (1).

18347209 is an equidigital number, since it uses as much as digits as its factorization.

18347209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 18347209 is about 4283.3642151935. The cubic root of 18347209 is about 263.7485026457.

The spelling of 18347209 in words is "eighteen million, three hundred forty-seven thousand, two hundred nine".