How it is calculated
The search runs up to the square root of what remains. One is not counted as prime. The minimum here is 2.
Number = product of prime factors
Where the numbers come from
- Number
Example
91 = 7 × 13, so it is composite. 17 is divisible only by itself and stays prime.
Questions
Is 1 prime?
No. A prime has exactly two different divisors: 1 and itself.
Is a repeated factor shown?
Yes. 12 is written as 2 × 2 × 3.
Very large numbers?
The ceiling is one billion, so the check can finish in the browser.