2205
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Number
$2205$ (two thousand, two hundred and five) is:
- $3^2 \times 5 \times 7^2$
- The $30$th heptagonal number after $1$, $7$, $18$, $34$, $55$, $81$, $112$, $\ldots$, $1525$, $1651$, $1782$, $1918$, $2059$:
- $2205 = \ds \sum_{k \mathop = 1}^{30} \paren {5 k - 4} = \dfrac {30 \paren {5 \times 30 - 3} } 2$
- The $3$rd odd abundant number after $945$, $1575$:
- $\map {\sigma_1} {2205} - 2205 = 2241 > 2205$
Arithmetic Functions on $2205$
| \(\ds \map {\sigma_0} { 2205 }\) | \(=\) | \(\ds 18\) | $\sigma_0$ of $2205$ | |||||||||||
| \(\ds \map {\sigma_1} { 2205 }\) | \(=\) | \(\ds 4446\) | $\sigma_1$ of $2205$ |