How many countries in the world and what is biggest country?

World Atlas says there are 195 countries in the world and Russia is the biggest.

The second part of your question is the easiest to answer. The Russian Federation is the world's largest country by far.

The number of countries is not as easy. There are places that exist and call themselves countries but may not be recognised by any other state or by very few states. The UN has 193 member states. To that list 'Wikipedia' adds two observer states who do not have full membership. They are the Holy See and Palestine. 'Wikipedia' also says there are eleven other states. Those include Taiwan which most states do not recognise but recognise instead mainland China.

195/Russia ......................................

There are 195 countries in the world and Russia is the biggest.