Here what you need to know is how to convert miliseconds into hours. For that, what is really important here is to use the Rule of Three, do you know it?
This rule is used when you have three terms on an equation and you need a fourth one, what you're going to do is, to add an X to the equation and then do the right math, see how this exercise is going to be developed below:
1 Hour equals to 3600000 miliseconds. With that said, now we are going to apply the rule, see how it works:
1h ---------- 3600000
X ----------- 1320000
Now you multiply X with 3600000 and 1 with 1320000, the result will be like this:
3600000X = 1320000
X = 1320000 / 3600000
X = 0,36h