What?
This is a quick reminder for myself on opening a CSV in MS Excel but without converting long numbers into exponential notations (which are incorrectly rounded anyway).

My Data: 
Account ID,Name,Phone,Record ID
1457102000000135533,Joel,00441234567890,1457102000000165989
1457102000000135566,Stanley,01709123456,1457102000000167543
1457102000000135608,David,00331234567890,1457102000000166795
My Excel: 
Account ID	Name	Phone	Record ID
1.4571E+18	Joel	4.41235E+11	1.4571E+18
1.4571E+18	Stanley	1709123456	1.4571E+18
1.4571E+18	David	3.31235E+11	1.4571E+18

How?
Firstly, save the CSV file as text file (*.TXT). This will stop MS Excel simply opening the CSV as if it knew what to do with it. It doesn't. Saving the data source as a text file means that Excel will prompt you what to do with each column:

1. Specify that the data is delimited
Excel Import Data Step 1 of 3

2. Specify the data is delimited by commas
Excel Import Data Step 2 of 3

3. Specify which columns should be imported as text (the long numbers and phone numbers)
Excel Import Data Step 3 of 3