255

Number
$255$ (two hundred and fifty-five) is:
 * $3 \times 5 \times 17$


 * The $25$th sphenic number after $30$, $42$, $66$, $70$, $\ldots$, $182$, $186$, $190$, $195$, $222$, $230$, $231$, $246$:
 * $255 = 3 \times 5 \times 17$


 * The $7$th positive integer solution after $1$, $3$, $15$, $104$, $164$, $194$ to $\phi \left({n}\right) = \phi \left({n + 1}\right)$:
 * $\phi \left({255}\right) = 128 = \phi \left({256}\right)$