Convert seconds to hours, minutes, seconds

How can I convert seconds to hours, minutes and seconds?

show_time() {
  ?????
}

show_time 36 # 00:00:36
show_time 1036 # 00:17:26
show_time 91925 # 25:32:05

I use the following function myself:

function show_time () {
    num=$1
    min=0
    hour=0
    day=0
    if((num>59));then
        ((sec=num%60))
        ((num=num/60))
        if((num>59));then
            ((min=num%60))
            ((num=num/60))
            if((num>23));then
                ((hour=num%24))
                ((day=num/24))
            else
                ((hour=num))
            fi
        else
            ((min=num))
        fi
    else
        ((sec=num))
    fi
    echo "$day"d "$hour"h "$min"m "$sec"s
}

Note it counts days as well. Also, it shows a different result for your last number.