Professor Cardy

Prime Number Calculator

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


30427 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: `30427` is 1 more than `30426` (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 `30427` is `925802329`. Subtracting 1, we get `925802328`. Note that `925802328 ÷ 24 = 38575097`.

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: `30427 = 15214^2 - 15213^2 = 231465796 - 231435369`

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: `30427` is of the form `4n-1`, where `n = 7607`.

The First 10,000 Prime Numbers