June 13 is the 164th day of the year, there are 201 days left in 2016

13 is a prime number, it is the 6th prime

13 is also a prime if the digits are reversed (31).

13 is a fibonacci number (0,1,1,2,3,5,8,13).

13 is the hypotenuse of a right traingle with sides of 5 & 12. 5, 12 & 13 can be used to test for right angles, like 3,4 & 5 can