Converting UTM to EPSG:5389

It could sound like a silly question, but I am having trouble converting points from UTM to long - lat (researching a bit, I found that I need is EPSG:5389 because is on the Southern side of Peru).
So, the data looks like this. In that way, many questions came to my mind:

  • I can create a polygon with the data shared; however, is advisable to first convert them to EPSG and then create the polygon?
  • Is there a way to convert all the coordinates of the polygon without unmerging them?

In any case, any suggestion that you can give me about the conversion will be highly appreciated.
Warm regards from Peru

Could you confirm what is the source of your coordinates and the coordinate reference system where they are defined? The numerical values do not make sense to me.

HI @rafael.guerra. Thanks for the comments.
Checking the original database, the data looks like this
Then, I added the first one with the third one, the second one with the fourth one and so on in order to obtain the data presented.
If you plot those on an excel file, you will find a perfect polygon in UTM.

In the UTM system, if I am not mistaken, 0 < X < 1_000_000 m and 0 < Y < 10_000_000 m. Your data goes beyond those bounds.

Yes. You are correct.
Researching a bit further in the data source, I found that those numbers are Msec Long and Msec Lat, respectively

In that case, you can divide your lat lon data in milliseconds by 3_600_000 to get lat lon in decimal degrees.