Question: is 2 a coprime number?
Answer: Every prime number is co-prime to each other: As every prime number have only two factors 1 and the number itself, the only common factor of two prime numbers will be 1. For example, 2 and 3 are two prime numbers. Factors of 2 are 1, 2 and factors of 3 are 1, 3. The only common factor is 1 and hence is co-prime.