6786
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Number
$6786$ (six thousand, seevn hundred and eighty-six) is:
- $2 \times 3^2 \times 13 \times 29$
- The $116$th triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $5995$, $6105$, $6216$, $6328$, $6441$, $6555$, $6670$:
- $6786 = \ds \sum_{k \mathop = 1}^{116} k = \dfrac {116 \times \paren {116 + 1} } 2$
- The $2$nd of the $7$th pair of triangular numbers whose sum and difference are also both triangular:
- $5460 = T_{104}$, $6786 = T_{116}$, $6786 + 5460 = T_{156}$, $6786 - 5460 = T_{51}$