ẖrj(“lying under”) + tp(“head”) + nswt(“king”), thus literally ‘(one) under the head of the king’. The written form demonstrates honorific transposition.
Jones, Dilwyn (2000) An Index of Ancient Egyptian Titles, Epithets and Phrases of the Old Kingdom (BAR International Series; 866 (I-II)), volume I-II, Oxford: Archaeopress, →ISBN, § 2874, page 788