18805 has 4 divisors (see below), whose sum is σ = 22572. Its totient is φ = 15040.

The previous prime is 18803. The next prime is 18839. The reversal of 18805 is 50881.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7569 + 11236 = 87^2 + 106^2 .

It is not a de Polignac number, because 18805 - 2¹ = 18803 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1876 + ... + 1885.

It is an arithmetic number, because the mean of its divisors is an integer number (5643).

2¹⁸⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

18805 is a deficient number, since it is larger than the sum of its proper divisors (3767).

18805 is an equidigital number, since it uses as much as digits as its factorization.

18805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3766.

The product of its (nonzero) digits is 320, while the sum is 22.

The square root of 18805 is about 137.1313239198. The cubic root of 18805 is about 26.5924149704.

The spelling of 18805 in words is "eighteen thousand, eight hundred five".