13

This number is a prime.

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Photo credit: Patrick Kik

In May 2001, Ford announced that it would replace 13 million tires on its Ford Explorer SUVs. [Caldwell]

The 13th of May 2011 will be a "double Friday the 13th," i.e., the sum of the digits of 5/13/2011 equals 13. The next time this will happen in a prime year is 1/13/2141. [Caldwell]