503

Number
$503$ (five hundred and three) is:


 * The $96$th prime number


 * The $18$th safe prime after $5$, $7$, $11$, $23$, $47$, $59$, $83$, $107$, $167$, $179$, $227$, $263$, $347$, $359$, $383$, $467$, $479$:
 * $503 = 2 \times 251 + 1$