/usr/share/source-highlight/number.lang is in libsource-highlight-common 3.1.7-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | number =
'\<[+-]?((0x[[:xdigit:]]+)|(([[:digit:]]*\.)?
[[:digit:]]+([eE][+-]?[[:digit:]]+)?))u?((int(?:8|16|32|64))|L)?\>'
|