577

Number
$577$ (five hundred and seventy-seven) is:


 * The $106$th prime number


 * The $9$th prime number of the form $n^2 + 1$ after $2$, $5$, $17$, $37$, $101$, $197$, $257$, $401$:
 * $577 = 24^2 + 1$