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:
 * $273 + 546 = 819$


 * The product with its reversal equals the product of another $3$-digit number with its reversal:
 * $273 \times 372 = 156 \times 651$