A very simple Flutter app that excepts user input, an integer, and checks to see if it is a Prime number.
A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. In other words, it has only two factors: 1 and itself.
For example. 5 is a prime number because there is no other way of writing it, only 1 x 5 or 5 x 1.