18005 has 8 divisors (see below), whose sum is σ = 23352. Its totient is φ = 13248.

The previous prime is 17989. The next prime is 18013. The reversal of 18005 is 50081.

18005 = T₄₆ + T₄₇ + ... + T₅₈.

It can be written as a sum of positive squares in 4 ways, for example, as 49 + 17956 = 7^2 + 134^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18005 - 2⁴ = 17989 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 74 + ... + 203.

It is an arithmetic number, because the mean of its divisors is an integer number (2919).

2¹⁸⁰⁰⁵ is an apocalyptic number.

It is an amenable number.

18005 is a deficient number, since it is larger than the sum of its proper divisors (5347).

18005 is a wasteful number, since it uses less digits than its factorization.

18005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295.

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 18005 is about 134.1827112560. The cubic root of 18005 is about 26.2098403298.

Adding to 18005 its reverse (50081), we get a palindrome (68086).

The spelling of 18005 in words is "eighteen thousand, five".