313

313 is a prime number, as is 10³¹³ + 313.

313 has a representation as a sum of two squares: 313 = 12² + 13².

If 313 people are chosen at random, then the probability that at least five of them will share the same birthday is greater than 50%.

313 is 100111001 in base 2 (binary).

311 and 313 form a twin prime pair.

313 is the hypotenuse of a primitive Pythagorean triple: 313² = 25² + 312².

In cartoons featuring Donald Duck, his car often sports the license plate number 313.

Source: Prime Curios!