The amount of space that 2^67 lines of text would take up in a .txt file depends on the length of each line.
line: 20000000000000000(17 char) 1LgpDjsqkxF9cTkz3UYSbdTJuvbZ45PKvx (34 char) 17+34 = 51
total number of characters as follows:
That is the worst way to store that informacion, to store it you need to store the data in its RAW data fot the address you only need the RMD hash in raw data it is only 20 bytes.
For the privatekey there is two options, don't store the private key because you will not sort the Addresses or Store the private key because you want to Sort the addresses
If you decide to store the private key you only need 9 bytes for it... in that case you only need 29 bytes.
If you decide NOT store the private key you only need 20 bytes for the hash rmd.
Whether there are 50 bytes or 20 bytes does not matter. Even if there are 20 bytes per line, we would still require 2,146,575 terabytes (TB) of storage space, which is still 25 percent of the entire storage capacity of Google servers. Anyway, let's leave these irrelevant discussions aside. We have people like @ProjectSe7en who are committed to supporting Such a excellent ideas. Let us move on and put an end to this topic.