How to pronounce interrupted

to cause or make a break in the continuity or uniformity of (a course, process, condition, etc.). to break off or cause to cease, as in the middle of something: He interrupted his work to answer the bell.

So, the “g” is not actually pronounced as a “g,” but it is not a “silent” letter either. It is actually pronounced in words such as “anger” and “linger”—but the same sort of thing does not happen in “strength” and “length” because of the “th” sound that follows immediately after.