July 18 is the 199th day of the year. There are 166 days left.

18 is a multiple of 9, 3, and 6, leading to suspicions that it will generate unending fractions (more later)

18 is the sum of 3 of its divisors, 3, 6, and 9
18 is argon, a noble gas
18 is the group containing noble (inert) gases in the periodic table