18

Eighteen (18) is a positive integer one more than 17 and one less than 19.

Properties
18 is an abundant composite number. Its factorization is 2*3^2. The previous abundant number is 12 and the next is 20.

18 is the sixth Lucas number, cetween 11 and 29.

18 is known for being the most common age at which you are considered an adult.