53 (fifty-three) is the natural number following 52 and preceding 54.

In mathematics

53 is a balanced prime, an isolated prime, the eighth Sophie Germain prime, and the ninth Eisenstein prime. It is a sexy prime with 47 and 59.

53 is the smallest prime number that does not divide the order of any sporadic group, inclusive of the six pariahs; it is also the first prime number that is not a member of Bhargava's prime-universality criterion theorem (followed by the next prime number 59), an integer-matrix quadratic form that represents all prime numbers when it represents the sequence of seventeen integers {2, ..., 47, 67, 73}.

53 is the smallest prime number with primitive roots 2, 3, and 5.

References