Find X=?

Well, I liked Hana Nakkache's solution, but there's one more solution to it!

---

Note that in the first row, there are $4$ primes, namely, $(2,3,5,7)$

In the second row, there are again $4$ primes, namely $(2,3,5,7)$

In the third row , there are $2$ primes, namely $(3,5)$

And lastly , in the last row, there is only $\boxed{1}$ prime, which is $5$ .

$X$ represents the number of closed areas by the numbers (colored in red) and thus it is equal to $1$ .