The largest data unit supported by GNU coreutils is currently quebibytes which is 2^100 bytes, or roughly 1,267,650,600,228,229,334,133,120 megabytes or 1,152,921,504,606,846,976 terrabytes. Ignoring the rounding errors of floating point calculations.

They estimate there is 44 zetabytes of electronic data in the world currently. One quebibyte is 24.4 million times larger than all then all digital data that currently exists in the world.