1638
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Number
$1638$ (one thousand, six hundred and thirty-eight) is:
- $2 \times 3^2 \times 7 \times 13$
- The $8$th Ore number after $1$, $6$, $28$, $140$, $270$, $496$, $672$:
- $\dfrac {1638 \times \map {\sigma_0} {1638} } {\map {\sigma_1} {1638} } = 9$
- and the $6$th after $1$, $6$, $14$, $270$, $672$ whose divisors also have an arithmetic mean which is an integer:
- $\dfrac {\map {\sigma_1} {1638} } {\map {\sigma_0} {1638} } = 84$