Adonikam in Smiths Bible Dictionary

The sons of Adonikam, 666 in number, were among those who returned from Babylon with Zerubbabel. Ezr 2:13; Ne 7:18; 1Esd 5:14 (B.C. 506-410.) The name is given as ADONIJAH in Ne 10:16

Link: https://bible-history.com/smiths/A/Adoni-kam+or+Adon-ikam/