1426

Number
$1426$ (one thousand, four hundred and twenty-six) is:


 * $2 \times 23 \times 31$


 * The $31$st pentagonal number after $1$, $5$, $12$, $22$, $35$, $\ldots$, $925$, $1001$, $1080$, $1162$, $1247$, $1335$:
 * $1426 = \displaystyle \sum_{k \mathop = 1}^{31} \left({3 k - 2}\right) = \dfrac {31 \left({3 \times 31 - 1}\right)} 2$