18431556818 has 4 divisors (see below), whose sum is σ = 27647335230. Its totient is φ = 9215778408.

The previous prime is 18431556811. The next prime is 18431556827. The reversal of 18431556818 is 81865513481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81865513481 = 41 ⋅1996719841.

It can be written as a sum of positive squares in only one way, i.e., 13172841529 + 5258715289 = 114773^2 + 72517^2 .

It is not an unprimeable number, because it can be changed into a prime (18431556811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4607889203 + ... + 4607889206.

Almost surely, 2^18431556818 is an apocalyptic number.

18431556818 is a deficient number, since it is larger than the sum of its proper divisors (9215778412).

18431556818 is an equidigital number, since it uses as much as digits as its factorization.

18431556818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9215778411.

The product of its digits is 921600, while the sum is 50.

The spelling of 18431556818 in words is "eighteen billion, four hundred thirty-one million, five hundred fifty-six thousand, eight hundred eighteen".