How are the NEO LEAP-1A engines attached on the A320?
This page shows a schematic of the mounts for the original A320.  There are 4 bolts and 2 shear pins at the front mount, and another 4 bolts and 2 shear pins at the aft mount. In general terms, the A320neo pylon and mount system design was kept very similar to the original A320 design.  So it's a good guess that the number of bolts is the same, although I was not able to find any source to confirm that.