18631309 has 2 divisors, whose sum is σ = 18631310. Its totient is φ = 18631308.

The previous prime is 18631271. The next prime is 18631331. The reversal of 18631309 is 90313681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11923209 + 6708100 = 3453^2 + 2590^2 .

It is a cyclic number.

It is not a de Polignac number, because 18631309 - 2⁹ = 18630797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18631399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9315654 + 9315655.

It is an arithmetic number, because the mean of its divisors is an integer number (9315655).

Almost surely, 2^18631309 is an apocalyptic number.

It is an amenable number.

18631309 is a deficient number, since it is larger than the sum of its proper divisors (1).

18631309 is an equidigital number, since it uses as much as digits as its factorization.

18631309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 18631309 is about 4316.4000046335. The cubic root of 18631309 is about 265.1028863575.

The spelling of 18631309 in words is "eighteen million, six hundred thirty-one thousand, three hundred nine".