18318478393 has 2 divisors, whose sum is σ = 18318478394. Its totient is φ = 18318478392.

The previous prime is 18318478319. The next prime is 18318478439. The reversal of 18318478393 is 39387481381.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13849288489 + 4469189904 = 117683^2 + 66852^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18318478393 is a prime.

It is not a weakly prime, because it can be changed into another prime (18318478693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9159239196 + 9159239197.

It is an arithmetic number, because the mean of its divisors is an integer number (9159239197).

Almost surely, 2^18318478393 is an apocalyptic number.

It is an amenable number.

18318478393 is a deficient number, since it is larger than the sum of its proper divisors (1).

18318478393 is an equidigital number, since it uses as much as digits as its factorization.

18318478393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3483648, while the sum is 55.

The spelling of 18318478393 in words is "eighteen billion, three hundred eighteen million, four hundred seventy-eight thousand, three hundred ninety-three".