Divisor Power Sum

Let $\sigma_{[k]}(n)$ be the sum of the $k$th powers of all positive divisors of $n$. If $\sigma_{[-1]} (144) = \frac{p}{q}$ where $p,q\in \mathbb{Z}^+$ and $\gcd(p,q) = 1$, find the value of $p+q$.