Lon Mae C. provided the correct answer in his response: 2,352,442,176 <= what I got with a calculator (under the assumption that multiplication was implied in the places where Lon put * in his interpretation of the problem) Making the same assumption, I used a calculator instead of Excel, just as verification of Lon Mae C's answer.
Another interpretation of the problem:
y = -4^3(-7)^5(3)^7
y = (-4)^(-21)^15^7
y = -2.8689245168416376253408193106276e-1328
With the inherent limitations on how you can present the problem here (e.g. there is no way to share a picture of the problem so we can see it in its intended form, and the type of problem you shared does not lend itself to easy interpretation that can be expressed adequately with the available character set.