66,066

Number
$66 \, 066$ (sixty-six thousand and sixty-six) is:


 * $2 \times 3 \times 7 \times 11^2 \times 13$


 * The $363$rd triangular number:
 * $66 \, 066 = \displaystyle \sum_{k \mathop = 1}^{363} k = \dfrac {363 \times \left({363 + 1}\right)} 2$


 * The $13$th palindromic triangular number after $1$, $3$, $6$, $55$, $66$, $171$, $595$, $666$, $3003$, $5995$, $8778$, $15 \, 051$


 * The $1$st of $2$ known palindromic triangular numbers whose index is also palindromic:
 * $66 \, 066 = T_{363} = \dfrac {363 \times \left({363 + 1}\right)} 2$