18685385509 has 16 divisors (see below), whose sum is σ = 21410611200. Its totient is φ = 15974192304.

The previous prime is 18685385489. The next prime is 18685385539. The reversal of 18685385509 is 90558358681.

It is a de Polignac number, because none of the positive numbers 2^k-18685385509 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18685385539) 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, 5898444 + ... + 5901610.

It is an arithmetic number, because the mean of its divisors is an integer number (1338163200).

Almost surely, 2^18685385509 is an apocalyptic number.

It is an amenable number.

18685385509 is a deficient number, since it is larger than the sum of its proper divisors (2725225691).

18685385509 is a wasteful number, since it uses less digits than its factorization.

18685385509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5112.

The product of its (nonzero) digits is 10368000, while the sum is 58.

The spelling of 18685385509 in words is "eighteen billion, six hundred eighty-five million, three hundred eighty-five thousand, five hundred nine".