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 $945$, $1575$:
 * $1 + 3 + 5 + 7 + 9 + 15 + 21 + 35 + 45 + 49 + 63 + 105 + 147 + 245 + 315 + 441 + 735 = 2241 > 2205$

Also see

 * Tau Function of 2205