590

Number
$590$ (five hundred and ninety) is:


 * $2 \times 5 \times 59$


 * The $20$th pentagonal number after $1$, $5$, $12$, $22$, $35$, $51$, $70$, $92$, $117$, $145$, $176$, $210$, $247$, $287$, $330$, $330$, $376$, $425$, $477$, $532$:
 * $590 = \displaystyle \sum_{k \mathop = 1}^{20} \left({3 k - 2}\right) = \dfrac {20 \left({3 \times 20 - 1}\right)} 2$