He was described as being among the highest of all angels (Brightest in the Sky) but was not explicitly named as a Archangel.
Not sure why he should be, when Archangels are only the second of the (IIRC) six different ranks of angels.
Let's see if I can remember them all, as close to in order as I can manage: angels, archangels, dominions, thrones, cherubim, seraphim
(Of course, this, too, depends on which particular branch of Christianity you listen to.)
