18481 has 2 divisors, whose sum is σ = 18482. Its totient is φ = 18480.

The previous prime is 18461. The next prime is 18493.

18481 is nontrivially palindromic in base 10.

It is the 56-th star number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18225 + 256 = 135^2 + 16^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 18481 - 2⁷ = 18353 is a prime.

It is a super-2 number, since 2×18481² = 683094722, which contains 22 as substring.

It is a nialpdrome in base 12.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (18401) 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 as a sum of consecutive naturals, namely, 9240 + 9241.

It is an arithmetic number, because the mean of its divisors is an integer number (9241).

2¹⁸⁴⁸¹ is an apocalyptic number.

It is an amenable number.

18481 is a deficient number, since it is larger than the sum of its proper divisors (1).

18481 is an equidigital number, since it uses as much as digits as its factorization.

18481 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 256, while the sum is 22.

The square root of 18481 is about 135.9448417558. The cubic root of 18481 is about 26.4388050389.

Subtracting from 18481 its product of digits (256), we obtain a square (18225 = 135²).

It can be divided in two parts, 1848 and 1, that added together give a square (1849 = 43²).

The spelling of 18481 in words is "eighteen thousand, four hundred eighty-one".