Given a natural number $q$, let $p=2^q-1$ be the $q$-th Mersenne number.

Let $R(q)$ be the minimal square root of $q$ modulo $p$, if one exists. In other words, $R(q)$ is the smallest positive integer $x$ such that $x^2-q$ is divisible by $p$.

For example, $R(5)=6$ and $R(17)=47569$.

Find $R(74207281)$. Give your answer modulo ${10}^9+7$.

Note: $2^{74207281}-1$ is prime.