Do prime numbers still work in base that’s isn’t 10?

Question

I’ve started reading a lot of sci-fi and the humans always attempt to communicate with aliens using prime numbers, but if they use a counting system that _isn’t_ base10, would the prime numbers still make sense?

In: 2249

Answer 1

Imagine taking 6 marbles. You can split that into 2 equal piles of 3. That tells you that 6 is not prime. It is 2×3. Now imagine taking 7 marbles. You can’t split this into equal piles of anything except 7 piles of 1. So 7 is prime. This is true regardless of the number system. Whether base 2 or 10 or 60. The number in each marble pile is equal or it’s not.