5 is the third prime number.
5 is the fifth Fibonacci number.
There are only 5 Platonic (regular) solids.
If a number is divisible by 5 it must end in a 5 or a 0.
5 is the hypotenuse of the smallest Pythagorean triangle.
Saraveca, a South American language, is the only one to base its counting system on 5.