13 is prime.

13 is a happy number.

13 is a Fibonacci number.

13 is a Tribonacci number with the first three numbers of 0, 0, 1.

13 is the smallest emirp.

13 is a member of the primitive, Pythagorean triples (5, 12, 13) and (13, 84, 85).

13 is a lucky number.

13 is the number of ways three competitors can finish a race if there can be ties.

The thirteen ways are:

1<2<3

1<3<2

2<1<3

2<3<1

3<1<2

3<2<1

1=2<3

1<2=3

1=2=3

1=3<2

2<1=3

2=3<1

3<1=2

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