23,209

Number
$23 \, 209$ (twenty-three thousand, two hundred and nine) is:


 * The $2591$st prime number


 * The index of the $26$th Mersenne prime after $2$, $3$, $5$, $7$, $13$, $\ldots$, $2203$, $2281$, $3217$, $4253$, $4423$, $9689$, $9941$, $11 \, 213$, $19 \, 937$, $21 \, 701$:
 * $M_{23 \, 209} = 2^{23 \, 209} - 1 \approx 4 \cdotp 029 \times 10^{6986}$