Professor Cardy

Prime Number Calculator

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Enter an integer (max. 1,000,000)


22739 is a prime number.

About the Calculator

This calculator performs the decomposition of a number into its prime factors and lists all its natural divisors. Enter an integer between 1 and 1,000,000.

Curiosities

1) Relation to multiples of 6: Every prime number greater than 3 is always one less or one more than a multiple of 6.
Example: `22739` is 1 less than `22740` (multiple of 6).

2) Square minus 1 divisible by 24: For every prime number greater than 3, if 1 is subtracted from its square, the result is always divisible by 24.
Example: The square of `22739` is `517062121`. Subtracting 1, we get `517062120`. Note that `517062120 ÷ 24 = 21544255`.

3) Difference of squares: Every prime number greater than 2 can be expressed as the difference of the squares of two consecutive natural numbers.
Example: `22739 = 11370^2 - 11369^2 = 129276900 - 129254161`

4) Form `4n+1` or `4n-1`: Except for the number 2, all prime numbers follow the pattern `4n+1` or `4n-1`, where `n` is a natural number.
Example: `22739` is of the form `4n-1`, where `n = 5685`.

The First 10,000 Prime Numbers