Michael is in the Bible, in several places. Especially in Revelation 12:
7 And there was war in heaven: Michael and his angels fought against the dragon; and the dragon fought and his angels,
8 And prevailed not; neither was their place found any more in heaven.
9 And the great dragon was cast out, that old serpent, called the Devil, and Satan, which deceiveth the whole world: he was cast out into the earth, and his angels were cast out with him.
Also the OT Book of the prophet Daniel also.
Angels are all over the bible, so your point is?
We do not pray to them period.