18001 has 4 divisors (see below), whose sum is σ = 18432. Its totient is φ = 17572.

The previous prime is 17989. The next prime is 18013. The reversal of 18001 is 10081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 10081 = 17 ⋅593.

It is an interprime number because it is at equal distance from previous prime (17989) and next prime (18013).

It is a cyclic number.

It is not a de Polignac number, because 18001 - 2⁹ = 17489 is a prime.

It is a Duffinian number.

18001 is a lucky number.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (18041) 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, 145 + ... + 238.

It is an arithmetic number, because the mean of its divisors is an integer number (4608).

2¹⁸⁰⁰¹ is an apocalyptic number.

It is an amenable number.

18001 is a deficient number, since it is larger than the sum of its proper divisors (431).

18001 is an equidigital number, since it uses as much as digits as its factorization.

18001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 430.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 18001 is about 134.1678053782. The cubic root of 18001 is about 26.2078992556.

Adding to 18001 its reverse (10081), we get a palindrome (28082).

The spelling of 18001 in words is "eighteen thousand, one".