2205

Number
$2205$ (two thousand, two hundred and five) is:
 * $3^2 \times 5 \times 7^2$


 * The $30$th heptagonal number after $1$, $7$, $18$, $34$, $5$, $81$, $112$, $\ldots$, $1525$, $1651$, $1782$, $1918$, $2059$:
 * $2205 = \displaystyle \sum_{k \mathop = 1}^{30} \left({5 k - 4}\right) = \dfrac {30 \left({5 \times 30 - 3}\right)} 2$


 * The $3$rd odd abundant number after $945$, $1575$:
 * $\sigma \left({2205}\right) - 2205 = 2241 > 2205$