convert sum of seconds to time h:mm:ss

,case when sum([CallsAnswered]) = 0 then 0 else sum([TalkTime]+[HoldTime]+[PostCallProcessingTime])/sum([CallsAnswered]) end as [IB HandleTime (Sec)]TalkTime, holdtime, postcallprocessingTime are all sum of seconds after dividing the sum of those, into the calls answered to get handle time, instead of getting 1300 seconds, how would I convert this to h:mm:ss? 1300 seconds = 0:21:40