18705 has 16 divisors (see below), whose sum is σ = 31680. Its totient is φ = 9408.

The previous prime is 18701. The next prime is 18713. The reversal of 18705 is 50781.

It is a happy number.

18705 is an esthetic number in base 12, because in such base its adjacent digits differ by 1.

It is not a de Polignac number, because 18705 - 2² = 18701 is a prime.

It is a super-3 number, since 3×18705³ = 19633349257875, which contains 333 as substring.

It is an alternating number because its digits alternate between odd and even.

18705 is an undulating number in base 12.

It is a plaindrome in base 6.

It is a nialpdrome in base 8.

It is a zygodrome in base 6.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 18705.

It is not an unprimeable number, because it can be changed into a prime (18701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 414 + ... + 456.

It is an arithmetic number, because the mean of its divisors is an integer number (1980).

It is a Poulet number, since it divides 2¹⁸⁷⁰⁴-1.

2¹⁸⁷⁰⁵ is an apocalyptic number.

18705 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18705 is a deficient number, since it is larger than the sum of its proper divisors (12975).

18705 is a wasteful number, since it uses less digits than its factorization.

18705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80.

The product of its (nonzero) digits is 280, while the sum is 21.

The square root of 18705 is about 136.7662239005. The cubic root of 18705 is about 26.5451940329.

The spelling of 18705 in words is "eighteen thousand, seven hundred five".