Meaning of the Sanskrit Word: prthum

  pṛthum—unto King Pṛthu    SB 4.15.5, SB 4.18.1
  pṛthum—unto Mahārāja Pṛthu    SB 4.22.1
  pṛthum—of King Pṛthu    SB 4.23.23

Can't find any compound Sanskrit words containing prthum.