Is 139 a prime number

Prime Numbers Chart and Calculator

A Prime Number is:

a whole number that cannot be made by multiplying other whole numbers

(if we can make it by multiplying other whole numbers it is a Composite Number)

And 1 is not prime and also not composite.

Here we see it in action:

2 is Prime, 3 is Prime, 4 is Composite (=2×2), 5 is Prime, and so on...


Here is a list of all the prime numbers up to 1,000:



  • Is 8 a Prime Number? No, because it can be made by 2×4=8
  • Is 73 a Prime Number? Yes, as no other whole numbers multiply together to make it.

Calculator ... Is It Prime?

Find out if a number is Prime or not (works on numbers up to 4,294,967,295):



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