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# If a prime was a number divisible by 1 and itself, could -1 be considered a prime, since it is only divisible by 1 and -1?

### 3 Answers

- ?Lv 74 years ago
prime numbers are defined to be > 1.

So neither -1 or 1 is a prime.

The definition is this way so that factorization of integers is unique.

- ?Lv 74 years ago
A prime number is a whole number greater than 1, whose only two whole-number factors are 1 and itself. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29. As we proceed in the set of natural numbers N = {1, 2, 3, ...}, the primes become less and less frequent in general.

- Old Man DirtLv 74 years ago
Any number that is prime number with a positive sign, is also a prime number with a negative sign.