18518309 has 2 divisors, whose sum is σ = 18518310. Its totient is φ = 18518308.

The previous prime is 18518303. The next prime is 18518341. The reversal of 18518309 is 90381581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18515809 + 2500 = 4303^2 + 50^2 .

It is a cyclic number.

It is not a de Polignac number, because 18518309 - 2⁸ = 18518053 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18518303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9259154 + 9259155.

It is an arithmetic number, because the mean of its divisors is an integer number (9259155).

Almost surely, 2^18518309 is an apocalyptic number.

It is an amenable number.

18518309 is a deficient number, since it is larger than the sum of its proper divisors (1).

18518309 is an equidigital number, since it uses as much as digits as its factorization.

18518309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 18518309 is about 4303.2904851985. The cubic root of 18518309 is about 264.5658442212.

The spelling of 18518309 in words is "eighteen million, five hundred eighteen thousand, three hundred nine".