dattatreyad dharer amsat
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The son of Krtavirya was Arjuna. He [Kartaviryarjuna] became the emperor of the entire world, consisting of seven islands, and received mystic power from Dattatreya, the incarnation of the Supreme Personality of Godhead. Thus he obtained the mystic perfections known as asta-siddhi.