189

Number
$189$ (one hundred and eighty-nine) is:


 * $3^3 \times 7$


 * The $9$th heptagonal number after $1, 7, 18, 34, 55, 81, 112, 148$:
 * $189 = 1 + 7 + 11 + 16 + 21 + 26 + 31 + 36 + 41 = \dfrac {9 \left({5 \times 9 - 3}\right)} 2$


 * The $36$th lucky number:
 * $1$, $3$, $7$, $9$, $13$, $15$, $21$, $\ldots$, $133$, $135$, $141$, $151$, $159$, $163$, $169$, $171$, $189$, $\ldots$