Free Tool
Prime Number Checker
Instantly check if any number is prime, get full factor breakdowns, batch-check multiple numbers, or find all primes in a range.
✓ Up to 10¹⁵
✓ Factor Breakdown
✓ Batch Check
✓ Range Finder
✓ Nearest Primes
Check a Single Number
Enter any positive integer up to 1,000,000,000,000,000 (10¹⁵)
Please enter a valid positive integer.
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Number
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Digits
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Factor Count
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Square Root
All Divisors
Batch Check Multiple Numbers
Enter numbers separated by commas, spaces, or new lines (up to 500 numbers)
Please enter at least one valid number.
Find All Primes in a Range
Enter a start and end value (range up to 100,000 for instant results)
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Please enter a valid range.
How to Use the Prime Number Checker
1
Single CheckEnter any number and get full prime analysis + all factors.
2
Batch ModePaste a list of numbers to check them all at once.
3
Range FinderDiscover every prime number between any two values.
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Instant ResultsAll math runs in your browser — no upload, no wait.