5985

Number
$5985$ (five thousand, nine hundred and eighty-five) is:
 * $3^2 \times 5 \times 7 \times 19$


 * The $45$th octagonal number, after $1$, $8$, $21$, $40$, $65$, $\ldots$, $3816$, $4033$, $4256$, $4485$, $4720$, $4961$, $5208$, $5461$, $5720$:
 * $5985 = \displaystyle \sum_{k \mathop = 1}^{45} \left({6 k - 5}\right) = 45 \left({3 \times 45 - 2}\right)$


 * The $10$th odd abundant number after $945$, $1575$, $2205$, $2835$, $3465$, $4095$, $4725$, $5355$, $5775$:
 * $\sigma \left({5985}\right) - 5985 = 6495 > 5985$