Show the phone number of the sanitarian who was responsible for inspection no.634597.
phone number refers to phone; sanitarian refers to title = 'Sanitarian'; inspection no.634597 refers to inspection_id = '634597'
SELECT T2.phone FROM inspection AS T1 INNER JOIN employee AS T2 ON T1.employee_id = T2.employee_id WHERE T1.inspection_id = 634597 AND T2.title = 'Sanitarian'