The as of last Tuesday, August 20, 2019, the USPTO issued U.S. Patent 10,390,470. That would seem to be the answer. A patent nerd would remember, however, that before patents were numbered about 9,957 patents — called the X patents — issued. A serious patent nerd would further know that as of August 20, 2019, for one reason or another, more than 48721 numbers did not correspond to issued patents. An uber patent nerd would know about factional patents, patents with fractional numbers issued between patents with whole numbers. There are at least four fractional patents in the era when patents were numbered.

So as of August 20, and until the next batch on August 27, the number may be 10,351,710.