Two is the only even prime number because other even numbers have at least three or more positive divisors. A number can only be considered prime when it only has two positive divisors: itself and 1.
Even numbers that are higher than 2 are composite numbers, because they have already themselves, 2 and 1 as definite divisors. There is an infinite number of primes, all of which (except the number 2) are odd numbers. A simple way to determine the primality of a number is through trial division, which is done by dividing the number starting with the divisor 2 and up to the number's square root. If any of the quotients doesn't have a remainder, then the number is not a prime number.
Learn MoreThe number 39 is not a prime number. The definition of a prime number states that it is a number that only has one and itself as factors. Because 39's factors are one, three, 13 and 39, it does not conform to the definition of a prime number.
Full Answer >The number 57 is not a prime number because it has factors other than one and 57. Three and 19 are also factors of 57.
Full Answer >The number 69 is not a prime number, as it has the factors of 3 and 23. A prime number is one which is only evenly divisible by itself and the number 1.
Full Answer >The number 1 is not a prime number. A prime number by definition is a positive integer greater than 1 that is evenly divisible by only itself and 1.
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