Jet engines are not measured in horsepower, but in units of thrust, usually pounds of thrust. It is not really possible to directly compare thrust to horsepower. The thrust numbers quoted by engine manufacturers are usually for static thrust at takeoff. Horsepower is defined as the ability to do 33,000 foot-pounds of work in one minute.
The problem is thrust is a static number, if the engine is bolted into a test stand and is roaring away making thrust, no movement is occurring and the engine is creating zero horsepower. Since horsepower is a measure of the ability to do work, then some movement must occur.
The 747 started off with 4 engines of 43,000 lbf thrust each. With each successive engine upgrade, thrust has grown to cater to the heavier aircraft. By the time the 747-400 came out, each engine had 53,000 lbf thrust. On the 747-8, each General Electric GEnx-2B67B engine provides 66,500 lbf thrust.
So once you have a particular thrust providing movement, you can convert thrust to horsepower. If you are moving at 33,000 feet per minute (345 mph) then each pound of thrust is equal to one horsepower. The B747-400 cruises at about 504 knots, that's about 580 mph. So for each engine, the horsepower produced is around 16,000 x 1.68 = 26,680 hp. Multiply that by 4 engines and you have the B747-400 needing something like 107,520 hp to fly at its cruising speed.
The Boeing 747-400 needs a total of 63,300 lbf of thrust to cruise at 567 mph. The work done in one minute is a force of 63,300 lbf over 49,896 feet in one minute or 3,158,416,800 lbf-ft per minute. One horsepower equals 33,000 lb-ft of work per minute. So the simple division gives us 95,710 HP for the equivalent horsepower to move a 747-400 at cruising speed.
Approximately 120,000 horsepower on take-off, approximately 60,000 horsepower while cruising, total from four engines. 747 wins a "tug of war" match against Arleigh Burke-class destroyer, which has "only" about 100,000 total horsepower from three engines.