Why is every prime number ($5$ and higher) divisible by $24$ (into a whole integer) when you square it and subtract $1$?
15915
For any prime $p > 3$, why is $p^2-1$ always divisible by 24?
79940
$\binom{p}{i}$ divisible by $p$, with $p$ prime
41277
Prime with digits reversed is prime?
112319
Sieve of Eratosthenes : why $\sqrt n$ work?
2522
Why is $a^n - b^n$ divisible by $a-b$?
18405
What is the greatest integer that divides $p^4-1$ for every prime number $p$ greater than $5$?
66623
Primes dividing $11, 111, 1111, ...$
28228
Is a prime factor of a number always less than its square root?
7415
why only square root approach to check number is prime
6700
An Olympiad problem in prime numbers :can we proof that "n" is prime in this case "
17194
$6^{(n+2)} + 7^{(2n+1)}$ is divisible by $43$ for $n \ge 1$
68145
If $p$ is an odd prime and $k$ an integer with $0<k<p-1$ then $1^k + 2^k + \ldots + (p-1)^k$ is divisible by $p$
130731
Is every integer the sum of distinct prime numbers?
146725
Are numbers of the form $n^2+n+17$ always prime
138259
Proof or disproof that every integer can be written as the sum of a prime and a square.
138890
Cool property of the number $24$
10364
Is $7$ the only prime followed by a cube?