Hastamalaka

Shankara had four primary disciples he installed as acharyas of the four maths.
Hastamalaka in Puri, Sureshvara in Sringeri, Padmapada in Dwaraka, Totaka in Jyotirmath (near Badrinath).

Read about Hastamalaka here
https://www.sringeri.net/history/sri-adi-shankaracharya/primary-disciples