66,056,806,460,865,066

Number
$66 \, 056 \, 806 \, 460 \, 865 \, 066$ is:


 * $2 \times 3 \times 7 \times 11 \times 1367 \times 6043 \times 17 \, 308 \, 303$


 * The $363 \, 474 \, 363$rd triangular number:
 * $66 \, 056 \, 806 \, 460 \, 865 \, 066 = \displaystyle \sum_{k \mathop = 1}^{363 \, 474 \, 363} k = \dfrac {363 \, 474 \, 363 \times \paren {363 \, 474 \, 363 + 1} } 2$


 * The $13$th palindromic triangular number after $0$, $1$, $3$, $6$, $66$, $3003$, $66 \, 066$, $617 \, 716$, $3 \, 544 \, 453$, $6 \, 172 \, 882 \, 716$, $30 \, 416 \, 261 \, 403$, $61 \, 728 \, 399 \, 382 \, 716$ whose index is itself palindromic:
 * $66 \, 056 \, 806 \, 460 \, 865 \, 066 = T_{363 \, 474 \, 363}$