313

Number
$313$ (three hundred and thirteen) is:


 * The $65$th prime number.


 * The $2$nd of the $20$th pair of twin primes, with $311$.


 * The $11$th palindromic prime:
 * $2, 3, 5, 7, 11, 101, 131, 151, 181, 191, 313, \ldots$


 * The $48$th happy number after $1, 7, 10, 13, 19, 23, \ldots, 226, 230, 236, 239, 262, 263, 280, 291, 293, 301, 302, 310$:
 * $313 \to 3^2 + 1^2 + 3^2 = 9 + 1 + 9 = 19 \to 1^2 + 9^2 = 1 + 81 = 82 \to 8^2 + 2^2 = 64 + 4 = 68 \to 6^2 + 8^2 = 36 + 64 = 100 \to 1^2 + 0^2 + 0^2 = 1$


 * The $9$th integer after $0, 1, 3, 5, 7, 9, 33, 99$ which is palindromic in both decimal and binary:
 * $313_{10} = 100 \, 111 \, 001_2$