18166817205 has 12 divisors (see below), whose sum is σ = 31489149900. Its totient is φ = 9688969152.

The previous prime is 18166817189. The next prime is 18166817233. The reversal of 18166817205 is 50271866181.

It can be written as a sum of positive squares in 2 ways, for example, as 7528338756 + 10638478449 = 86766^2 + 103143^2 .

It is not a de Polignac number, because 18166817205 - 2⁴ = 18166817189 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45), and also a Moran number because the ratio is a prime number: 403707049 = 18166817205 / (1 + 8 + 1 + 6 + 6 + 8 + 1 + 7 + 2 + 0 + 5).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 201853480 + ... + 201853569.

It is an arithmetic number, because the mean of its divisors is an integer number (2624095825).

Almost surely, 2^18166817205 is an apocalyptic number.

18166817205 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18166817205 is a deficient number, since it is larger than the sum of its proper divisors (13322332695).

18166817205 is a wasteful number, since it uses less digits than its factorization.

18166817205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 403707060 (or 403707057 counting only the distinct ones).

The product of its (nonzero) digits is 161280, while the sum is 45.

The spelling of 18166817205 in words is "eighteen billion, one hundred sixty-six million, eight hundred seventeen thousand, two hundred five".