The correct number is 193.
At the moment there is a total of 193 countries that are members of the United Nations, and these countries are also part of the United Nations General Assembly.
For one state to become a member of the United Nations, there is a set of strict criteria, stated in the United Nations Charter, Chapter number 2, article number 4.
According to it, all peace-loving countries are eligible of being a member of the United Nations, under the condition they accept all obligations included in the Chapter, and the admission will be accepted by decision of the Assembly upon being recommended from the Security Council.