I'm using this permalink for all /%category%/%postname%/. Due to some reasons i want to change permalink to /anyword/%post_id%/ for a single category and it's sub-categories.

i.e. For all - permalink is like this - www.example.com/categoryname/postname

and i want to change permalink for "world" category and it's subcategories like "india","u.s." etc. to this - www.example.com/world/34343

I don't want to affect any other permalink structure and permalinsk.