Yes.
No, only square numbers have an odd number of factors.
The numbers with only three factors are squares of prime numbers.
Factors come in pairs. It is only in the case of a square number that the two middle factors are equal and so are counted only once.
A number has exactly three factors if and only if it is the square of a prime number.
There are square numbers (numbers which are a square of an integer), such as 4. It's factors, listed are 1, 2, and 4. All square numbers have an odd number of factors. Then there's 1, which has only 1 factor: 1. All other numbers have an even number of factors. Prime numbers will have only 2 factors (2 is even).
The factors of 18 are 1, 2, 3, 6, 9, and 18. The only square number of those numbers is 9.
4 is the only square number that is a factor of 84. No square number is a factor of 105.
Different square numbers have different sets of factors. The only thing they all have in common is an odd number of factors.
Every square number (except 1) is composite. Prime numbers only have two factors, one and the numbers themselves. Since square numbers also have at least the square roots as factors, they have to be composite.
It depends what square number you're looking at. The square number 25 has only three factors (1, 5 and 25) but the square number 16 has 5 (1, 2, 4, 8 and 16.) A key point is that the factors don't pair up. There is always one middle factor that is the square root of the number and so cannot pair with any other factor. This means that all square numbers have an odd number of factors, while other numbers have an even number of factors.
Okay, whoever said that a number can only have an even number of factors IS Wrong Take a prime number and square it. If you square a prime number, the number you get will only have 3 factors. For example, if I squared the number 3, I would get 9. 9 only has three factors: 9, 3, 1 Any prime number squared has Three factors.
No. 81=9*9=3*27=1*81 81 has 5 factors and is a square number. 36=6*6=3*12=1*36=2*18=4*9 36 has 9 factors and is a square number. This doesn't mean that no square numbers have exactly 3 factors though, because: 9=3*3=1*9 9 has 3 factors and is a square number. 4=2*2=1*4 4 has 3 factors and is a square number. All square numbers have an odd number of factors though (because they have a whole number which multiplies by itself to get the number). Factors are whole numbers only, and not decimals. Hope this helps :)