4010

Number
$4010$ (four thousand and ten) is:


 * $2 \times 5 \times 401$


 * The magic constant of a magic square of order $20$, after $1$, $(5)$, $15$, $34$, $\ldots$, $870$, $1105$, $1379$, $1695$, $2056$, $2465$, $2925$, $3439$:
 * $4010 = \displaystyle \dfrac 1 {20} \sum_{k \mathop = 1}^{20^2} k = \dfrac {20 \paren {20^2 + 1} } 2$