8,388,607

Number
$8 \, 388 \, 607$ (eight million, three hundred and eighty-eight thousand, six hundred and seven) is:


 * $47 \times 178 \, 481$


 * The $2$nd Mersenne number after $2047$ which is composite:
 * $8 \, 388 \, 607 = 2^{23} - 1 = 47 \times 178 \, 481$


 * It was discovered by to be composite in $1640$.


 * The $9$th Mersenne number after $3$, $7$, $31$, $127$, $2047$, $8191$, $131 \, 071$, $524 \, 287$:
 * $8 \, 388 \, 607 = 2^{23} - 1$