273

Number
$273$ (two hundred and seventy-three) is:


 * $3 \times 7 \times 13$


 * The $51$st lucky number:
 * $1, 3, 7, 9, 13, 15, 21, \ldots, 219, 223, 231, 235, 237, 241, 259, 261, 267, 273, \ldots$


 * The $3$rd of $4$ integers $n$ such that $n + 2 n$ can be expressed as a sum using each of the digits $1$ to $9$ exactly once each:
 * $273 + 546 = 819$