18405731985 has 16 divisors (see below), whose sum is σ = 29476140864. Its totient is φ = 9807400512.

The previous prime is 18405731923. The next prime is 18405732017. The reversal of 18405731985 is 58913750481.

It is not a de Polignac number, because 18405731985 - 2¹⁰ = 18405730961 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 544927 + ... + 577716.

It is an arithmetic number, because the mean of its divisors is an integer number (1842258804).

Almost surely, 2^18405731985 is an apocalyptic number.

18405731985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18405731985 is a deficient number, since it is larger than the sum of its proper divisors (11070408879).

18405731985 is a wasteful number, since it uses less digits than its factorization.

18405731985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1123744.

The product of its (nonzero) digits is 1209600, while the sum is 51.

The spelling of 18405731985 in words is "eighteen billion, four hundred five million, seven hundred thirty-one thousand, nine hundred eighty-five".