Prime Number Checker
Check if a number is prime, see its factors, the next and previous prime, and list primes up to N.
Result
How to use
- 1
Type a whole number.
- 2
See whether it is prime, its factors and the nearest primes.
- 3
Change the limit to list all primes up to that number.
Questions
What is a prime number?
A whole number greater than 1 whose only factors are 1 and itself — like 2, 3, 5, 7, 11 and 13.
Is 1 a prime number?
No. 1 has only one factor, so it is neither prime nor composite. 2 is the smallest and the only even prime.
How many primes are there below 100?
25 — 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.
About this Prime Checker tool
Prime Number Checker — Check if a number is prime, see its factors, the next and previous prime, and list primes up to N. It is one of 200 free tools on namasivayam.in, made by software engineer Namasivayam Vadivelan for everyday use in India.
Everything is calculated instantly in your browser: nothing you type or upload is sent to any server, there is no sign-up, and it works on mobile and desktop. Type a whole number.
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Results are estimates to help you plan. They are not financial, tax or medical advice.