**Read my second reply before trying this**
So no matter what you open the file in it is in scientific notation? Or are you only trying Excel? Because this is an issue with Excel usually. Depending how long the numbers are Excel really does not like playing with things over 15 digits. In my testing this happens with all numbers that have 12 or more digits.
I use the web version of Excel, this may be slightly different with the actual program. I made sure this was a good test because this data is pulled from Quick Base where I had numbers stored that Excel turned into scientific notation when loaded in. So it should work for you just the same.
What you can do to convert your numbers back to the full number, and this needs to be done on each and every column with a number, is use the Number Format option. Simply right click the column and select "Number Format..." then select the options as my screenshot shows. This will convert the numbers for you. It fixed numbers for me that Excel had changed to scientific format as well as adding decimals that didn't belong.