761

761 is a prime number. It is a Sophie Germain prime because 2 x 761 + 1 = 1523 is also prime.

761 is a centered square number.

761 is the sum of all primes numbers up to 79.

761 has a representation as a sum of two squares: 761 = 19² + 20².

761 is the hypotenuse of a primitive Pythagorean triple: 761² = 39² + 760².

A sequence of six nines (known as the Feynman point) begins immediately after the 761st decimal place of pi. Physicist Richard Feynman expressed a wish to memorize the digits of pi as far as that point so that when reciting them he would be able to end with ". . . nine, nine, nine, nine, nine, nine, and so on."

Source: Prime Curios!