Answer:
29
Explanation:
The squares cannot be very big. For example the difference between 10^ and 11^2 = 100 to 121 which is a difference of 21.
What you are talking about is x + 4 prime + 7 next square.
Write the squares
1
4
9
16
25
36
add 4 to get to the prime, add 7 to get to the next square. That's 12
1 and 4 have a difference of 3 too small
4 and 9 have a difference of 5 too small
9 and 16 have a difference of 7 which is too small
16 and 25 have a difference of 9 which just a little too small.
25 and 36 has a difference of 11. Just right
25 + 4 = 29
29 + 7 = 36
Just right.