Professor Cardy

Prime Number Calculator

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


68683 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: `68683` is 1 more than `68682` (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 `68683` is `4717354489`. Subtracting 1, we get `4717354488`. Note that `4717354488 ÷ 24 = 196556437`.

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: `68683 = 34342^2 - 34341^2 = 1179372964 - 1179304281`

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: `68683` is of the form `4n-1`, where `n = 17171`.

The First 10,000 Prime Numbers