18311509 has 2 divisors, whose sum is σ = 18311510. Its totient is φ = 18311508.

The previous prime is 18311471. The next prime is 18311549. The reversal of 18311509 is 90511381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17892900 + 418609 = 4230^2 + 647^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18311509 is a prime.

It is a super-2 number, since 2×18311509² = 670622723714162, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18311549) 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, 9155754 + 9155755.

It is an arithmetic number, because the mean of its divisors is an integer number (9155755).

Almost surely, 2^18311509 is an apocalyptic number.

It is an amenable number.

18311509 is a deficient number, since it is larger than the sum of its proper divisors (1).

18311509 is an equidigital number, since it uses as much as digits as its factorization.

18311509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1080, while the sum is 28.

The square root of 18311509 is about 4279.1949009130. The cubic root of 18311509 is about 263.5773242890.

The spelling of 18311509 in words is "eighteen million, three hundred eleven thousand, five hundred nine".