Ratio of 2016 to Aliquot Sum

Theorem
$2016$ has the property that its ratio to the sum of its aliquot parts is $4 : 9$.

Proof
The aliquot parts of an integer $n$ are its divisors of $n$ which are strictly less than $n$.

That is, the aliquot parts of $2016$ are the $\sigma$ function of $2016$ minus $2016$.

Thus: