How to check prime number in Java. In this tutorial, we are going to write a Java program to check whether a number is prime or not. Also In this tutorial, we’ll discuss multiple approaches and their time complexity to solve this problem.

Before writing a program, let’s quickly understand what is a prime number.

### What is Prime Number?

A prime number is a number that is greater than 1 and it has no positive divisors other than 1 and itself.

For example – 3, 13, 7 is a prime number, as it’s divisible by 1 and itself. Similarly, 29, 19 etc. are also prime numbers.

6 is not a prime number as it’s divisible by 1, 2, 3 and 6.

2 is the only even prime number.