1326

Number
$1326$ (one thousand, three hundred and twenty-six) is:
 * $2 \times 13 \times 51$


 * The $51$st triangular number after $1$, $3$, $6$, $10$, $15$, $\ldots$, $990$, $1035$, $1081$, $1128$, $1176$, $1225$, $1275$:
 * $1326 = \displaystyle \sum_{k \mathop = 1}^{51} k = \dfrac {51 \times \left({51 + 1}\right)} 2$


 * The $26$th hexagonal number after $1$, $6$, $15$, $28$, $45$, $66$, $91$, $\ldots$, $703$, $780$, $861$, $946$, $1035$, $1128$, $1225$:
 * $1326 = \displaystyle \sum_{k \mathop = 1}^{26} \left({4 k - 3}\right) = 26 \left({2 \times 26 - 1}\right)$


 * The $5$th hexamorphic number after $1$, $45$, $66$, $1225$:
 * $1326 = H_{26}$