I got 43622 AIR and 11300 OBC rank which branch can i get in nit wrangal ? and my interest is mathematics

If you're talking about JEE mains 2020. The closing rank of different NITs various every year. You can have a look at the previous year cutoff of different NITs. https://engineering.careers360.com/articles/jee-main-cutoff-for-top-nits

It depends on you either you want to persue engineering or any other graduate degree in mathematics. There are various branches of engineering which requires good knowledge of mathematics such as civil, chemical, mechanical etc. Think about it and come with your own decision.

And if you want to know the chances of admission in different institutes have a look at the college predictor tool it will help you. The link of which is below- https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer