Ratio of 2016 to Aliquot Sum

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

Proof
The aliquot sum of an integer $n$ is the integer sum of the proper divisors of $n$.

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

Thus: