297

Number
$297$ (two hundred and ninety-seven) is:


 * $3^3 \times 11$


 * The $6$th Kaprekar number after $1$, $9$, $45$, $55$, $99$:
 * $297^2 = 88 \, 209 \to 88 + 209 = 297$


 * The $4$th Kaprekar triple after $1$, $8$, $45$:
 * $297^3 = 26 \, 198 \, 073 \to 26 + 198 + 073 = 297$


 * The $55$th lucky number:
 * $1$, $3$, $7$, $9$, $13$, $15$, $21$, $\ldots$, $237$, $241$, $259$, $261$, $267$, $273$, $283$, $285$, $289$, $297$, $\ldots$