A SR22 pilot reported engine malfunction and diversion to a nearby airport.

Narrative

I departed ZZZ1 direct to ZZZ2 with 3 souls on board. Ceilings and visibility were unlimited and winds aloft were out of the northwest. We climbed direct to 11;500 feet and had been in the cruise phase for about 5 minutes and the engine started vibrating. I was flying per the manufacturer's recommendation at 30.5' HG and 17 GPH fuel flow which is LOP and about 78% power. I enriched the mixture and pulled power back and the engine continued to run very rough. I shut off the auxiliary fuel pump and the engine smoothed out some but still vibrating. After reviewing CHT's and EGT's it was evident that cylinder #5 was dead and at that point I decided to not try and increase power from the engine by changing mixture or throttle. The nearest airport was ZZZ which was 10 miles south. I disabled Autopilot and turned towards the airport. I listened to AWOS and called on the CTAF frequency to alert any pilots in the vicinity that we were descending for an urgent landing. I circled down over the airport slowly; not wanting to overspeed the engine by rapid descent and positioned for a landing on Runway XX. I made a smooth landing and was able to taxi off of the runway and to the ramp before shutting the engine down. As I taxied in with the engine at 700 rpm; I could hear a steel on steel clanking in the engine. A large amount of oil drained out of the cowling within 10 minutes of shutdown. All passengers were safe and the aircraft undamaged other than mechanical problems in the engine.