Convert milliseconds into a date and store as a date variable

[sasrsc]

I have a Date Time variable in a SP List called 'Occ Out Date' and I'm creating the variable MaxDate as the Max value. All OK. 
This by default creates a number which I assume is milliseconds.

UpdateContext(
    {
        MaxDate: Max(
            ThisAttendeeHotels,
            'Occ Out Date'
        )
    }
);

 
I can render this on a page in a label by doing...

" Max Check Out=" & Text(MaxDate,"[$-en-US]mm/dd/yyyy")

When I view the variable I see "it's a number" variable and the value is 16020273600000 which when converted in the label displays what I'd expect. 
All good so far...

But now I want to see the date difference between the MaxDate variable and a true date/time variable.
I'm not comparing the time only the date.
In my global variables I have a DateTime variable called DepartDate that reads 5/6/2021 5:21 PM.

There are 2 questions...
1) How do I compare the date value of the MaxDate and the DepartDate's?
2) Wouldn't it make more sense to create the MaxDate as a DateTime variable in the very beginning - if so, what would I do to create that as such in the very beginning?

[Pstork1 · Accepted solution]

To convert MaxDate into a DateTime value use the DateTimeValue() function.  Then you can get the difference in days using the following.

DateDiff(DepartDate,DateTimeValue(Text(MaxDate,"[$-en-US]mm/dd/yyyy") ),Days)

Its an easy enough conversion and I don't see a reason to change what you are doing if the values display correctly in the label.

[sasrsc]

Thanks PStork...

In the end I took your advice and kept the variable as a number...
I'm actually displaying an icon as a warning when they don't match...with the visible property reflecting...(in case this helps others)
DepartDate is a date/time variable
MaxDate is a number (reflected in milliseconds)

If(DateDiff(DepartDate,DateTimeValue(Text(MaxDate,"[$-en-US]mm/dd/yyyy") ),Days) <> 0, true,false)