The question "what number is Texas?" is based on a misunderstanding. Texas is a state, not a number.
However, if you mean order of admission to the Union:
If you mean population rank (2023): 2nd (after California).
If you mean area rank: 2nd (after Alaska).
If you mean electoral votes: 40 (2nd after California's 54).
Texas is many things—a state, a former republic, an economic powerhouse—but it is not a number.