18307309 has 2 divisors, whose sum is σ = 18307310. Its totient is φ = 18307308.

The previous prime is 18307307. The next prime is 18307319. The reversal of 18307309 is 90370381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18275625 + 31684 = 4275^2 + 178^2 .

It is a cyclic number.

It is not a de Polignac number, because 18307309 - 2¹ = 18307307 is a prime.

Together with 18307307, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18307301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9153654 + 9153655.

It is an arithmetic number, because the mean of its divisors is an integer number (9153655).

Almost surely, 2^18307309 is an apocalyptic number.

It is an amenable number.

18307309 is a deficient number, since it is larger than the sum of its proper divisors (1).

18307309 is an equidigital number, since it uses as much as digits as its factorization.

18307309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 31.

The square root of 18307309 is about 4278.7041262513. The cubic root of 18307309 is about 263.5571710362.

The spelling of 18307309 in words is "eighteen million, three hundred seven thousand, three hundred nine".