Revelation 9:16
And the number of the army of the horsemen were two hundred thousand thousand: and I heard the number of them.
Cross-reference
Revelation 7:4
Contrast
Revelation 7:4 records 144,000 sealed from Israel, contrasting with the 200 million demonic army here — saved vs. destroyers.
Daniel 7:10
Allusion
In Daniel 7:10, 'ten thousand times ten thousand' stand before God — this similar myriads-of-myriads number compares to the 200 million cavalry here.