18321566403 has 16 divisors (see below), whose sum is σ = 28019375360. Its totient is φ = 10431667296.

The previous prime is 18321566399. The next prime is 18321566423. The reversal of 18321566403 is 30466512381.

It is not a de Polignac number, because 18321566403 - 2² = 18321566399 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18321566423) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1569013 + ... + 1580646.

It is an arithmetic number, because the mean of its divisors is an integer number (1751210960).

Almost surely, 2^18321566403 is an apocalyptic number.

18321566403 is a deficient number, since it is larger than the sum of its proper divisors (9697808957).

18321566403 is a wasteful number, since it uses less digits than its factorization.

18321566403 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3149946.

The product of its (nonzero) digits is 103680, while the sum is 39.

The spelling of 18321566403 in words is "eighteen billion, three hundred twenty-one million, five hundred sixty-six thousand, four hundred three".