4423

Number
$4423$ (four thousand, four hundred and twenty-three) is:


 * The $602$nd prime number


 * The index of the $20$th Mersenne prime after $2$, $3$, $5$, $7$, $13$, $17$, $19$, $31$, $61$, $89$, $107$, $127$, $521$, $607$, $1279$, $2203$, $2281$, $3217$, $4253$:
 * $M_{4423} = 2^{4423} - 1 \approx 2 \cdotp 855 \times 10^{1331}$