As a pure quantity representing a real-world value, probably not very often, but just as a series of bits or a more abstract quantity like a memory address, it

As a pure quantity representing a real-world value, probably not very often, but just as a series of bits or a more abstract quantity like a memory address, it will often go above 2^56. Many algorithms and binary file encodings use 64 bit integers so interfacing with them in Javascript is hard.