Which among the following is NOT a prime number?

Which of the following is a prime number?

Which one of the following cannot be the square of a natural number?

Which of the following does NOT express the square of 11 in terms of sum of odd numbers?

Which of the following is the unit digit in the product of [(341)⁴⁹¹ × (625)³¹⁷ × (6374)¹⁷⁹³]?

Consider the following numbers : 1. 437 2. 797 3. 1073 How many of the above numbers are prime ?