Conjecture: Every prime number is the difference between a prime number and a power of $2$
Solution 1:
This question discusses the existence/infinitude of primes $p$ that can be written in the form $$p = q \pm 2^n$$ where $q$ is a prime and $n \in \mathbb{Z}^+$.
In particular for $p = q - 2^n$, Gjergji Zaimi mentions in a comment to his asnwer that $$p = 47,867,742,232,066,880,047,611,079$$ is a counterexample.