Prime Number Checker
Is your number prime?
Prime Number Checker
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What This Calculator Does
The Prime Number Checker determines if a number is prime and lists its prime factors if it is not. A prime number is only divisible by 1 and itself.
How It Works
Test divisibility up to the square root. If no divisor is found, the number is prime.
Example
97 is prime. 100 = 2^2 x 5^2. 13 is prime.
Formula
Check divisibility up to sqrt(n)Reading the Results
Is Prime?
Yes if the number is only divisible by 1 and itself. No otherwise.
Number of Factors
The total count of positive divisors. Primes have exactly 2 factors.
Frequently Asked Questions
How do I check if a number is prime?
Check divisibility from 2 to the square root of the number. If none divide evenly, it is prime.
Why is 1 not prime?
By mathematical definition, a prime must have exactly two distinct positive divisors. 1 has only one.
What are prime factors?
Prime factors are the prime numbers that multiply together to give the original number.