643

Number
$643$ (six hundred and forty-three) is:


 * The $117$th prime number


 * The larger of the $29$th pair of twin primes:
 * $643 - 641 = 2$


 * The $38$th left-truncatable prime after $2$, $3$, $5$, $7$, $\ldots$, $443$, $467$, $523$, $547$, $613$, $617$

Also see