convert number to HH:MM

I create an input_number -> timer_countdown
I want convert the number to HH:MM

The conversion to minutes is working but the hours receive unknown, I try multiple way to convert it

MY Sensor:

- platform: template
    sensors:
     timer_int:
      value_template: "{{ states('input_number.timer_countdown') | int }}"
     timer_countdown_min:
      value_template: "{{ states('input_number.timer_countdown') | int %60}}"

    ### what is the correct way to do this operation ?###
     timer_countdown_hour:
      value_template: "{{ states('sensor.timer_int') - states('sensor.timer_countdown_min') / 60 }}"