Prime Number Checker
Fill in the value and the answer updates as you type.
How the Prime Number Checker works
A prime number has exactly two divisors: 1 and itself. The checker tests divisors up to the square root of the number. It accepts whole numbers up to one trillion.
Inputs and results
The Prime Number Checker takes 1 input and gives 3 results.
What you enter
- Whole number — starts at 97.
What you get
- Is it prime?
- Smallest prime factor
- Next prime number
Example: Prime Number Checker with the starting values
With whole number 97, the calculator returns:
| Is it prime? | Yes, it is prime |
|---|---|
| Smallest prime factor | 97 |
| Next prime number | 101 |
Change any value above and the results update straight away.
Prime Number Checker FAQ
How do I use the Prime Number Checker?
Enter whole number in the fields, then read is it prime?, smallest prime factor and next prime number in the result panel. The answer updates as you type, and you can press Calculate or Enter to refresh it. Use “Copy link” to share your exact numbers with someone else.
What does the Prime Number Checker calculate?
Check if a number is prime and find the next prime. It returns is it prime?, smallest prime factor and next prime number from the 1 value you provide.
What values does the Prime Number Checker start with?
It opens with whole number 97 so you can see a working result straight away. Replace them with your own numbers, or press Reset to return to these starting values.
Is the Prime Number Checker free and private?
Yes. It is free, needs no account, and runs in your browser, so nothing you type is sent to or stored on our servers. See the Privacy Policy for details.
Can I rely on the Prime Number Checker for important decisions?
Treat the result as a well-rounded estimate. Real situations often have details a general calculator cannot know, so confirm important decisions with a qualified professional. See the Disclaimer for more.