To read big integer number in CSV file as 64bit integer, first read it as character.

It can be done by specifying Column Types as y=‘c’, where y is the column name, and ‘c’ means character, and disabling Detect Data Type like following screenshot.

As a result, now you have the y column as character data.

Then, you can convert the character into 64 bit integer with as.integer64 function like following.

Now you have the column y as integer64 type.