There is some dispute as to how long he reigned, based on disputes among various copies of the Assyrian King List.
The Nassouhi King List, sometimes considered to be older than the other versions of the King List we have, gives him 13 years of reign, but the other king lists give him only 3.
More recent scholarship has tended to support the shorter reign, in which case he reigned from 1182 to 1180 BCE (alternately, he reigned from 1192 to 1180 BCE).
He was an usurper, the great-great-great grandson of Adad-nirari I.
He seized the throne from Enlil-kudurri-usur, a son of the powerful king Tukulti-Ninurta I.
After his reign of either three or thirteen years, Ninurta-apal-Ekur is succeeded by his son, Ashur-dan I.