18418 has 4 divisors (see below), whose sum is σ = 27630. Its totient is φ = 9208.

The previous prime is 18413. The next prime is 18427. The reversal of 18418 is 81481.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 81481 = 17 ⋅4793.

It can be written as a sum of positive squares in only one way, i.e., 17689 + 729 = 133^2 + 27^2 .

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 plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (18413) by changing a digit.

18418 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4603 + ... + 4606.

2¹⁸⁴¹⁸ is an apocalyptic number.

18418 is a deficient number, since it is larger than the sum of its proper divisors (9212).

18418 is an equidigital number, since it uses as much as digits as its factorization.

18418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9211.

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

The square root of 18418 is about 135.7129323241. The cubic root of 18418 is about 26.4087283658.

Adding to 18418 its reverse (81481), we get a palindrome (99899).

It can be divided in two parts, 1841 and 8, that added together give a square (1849 = 43²).

The spelling of 18418 in words is "eighteen thousand, four hundred eighteen".