"this answer implies that primes are the same regardless of base"
Right. If you have some quantity of apples, then can you lay them out in a regular rectangular-shaped grid (more than 1 apple wide)? If not, the quantity is prime. You can count the apples in any base you like.
Right. If you have some quantity of apples, then can you lay them out in a regular rectangular-shaped grid (more than 1 apple wide)? If not, the quantity is prime. You can count the apples in any base you like.