Professor Cardy

Prime Number Calculator

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


66523 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: `66523` is 1 more than `66522` (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 `66523` is `4425309529`. Subtracting 1, we get `4425309528`. Note that `4425309528 ÷ 24 = 184387897`.

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: `66523 = 33262^2 - 33261^2 = 1106360644 - 1106294121`

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: `66523` is of the form `4n-1`, where `n = 16631`.

The First 10,000 Prime Numbers