It is known that the number $\displaystyle 2^{13-1}$ is prime.

Is $\displaystyle n=2^{17-16}$

With all the natural numbers, the number of divisors of n is:

a) 6

b) 10

c) 5

d) 8

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- Mar 20th 2009, 12:09 PMApprentice123Set of numbers
It is known that the number $\displaystyle 2^{13-1}$ is prime.

Is $\displaystyle n=2^{17-16}$

With all the natural numbers, the number of divisors of n is:

a) 6

b) 10

c) 5

d) 8

- Mar 20th 2009, 12:59 PMHallsofIvy
- Mar 20th 2009, 01:01 PMShowcase_22
Is $\displaystyle 2^{13-1}$ prime?

$\displaystyle 2^{13-1}=2^{12}$ which is divisible by 2.

Do you mean $\displaystyle 2^{13}-1$?

Do you also mean something like this:

$\displaystyle 2^{17}-16=2^{17}-2^4=2^4(2^{13}-1)$

Hence it's divisible by 10 numbers: $\displaystyle 2,2^2,2^3,2^4$,$\displaystyle 2^{13}-1$ and $\displaystyle 2^{13}-1$ multiplied by $\displaystyle 2,2^2$ and $\displaystyle 2^3$ AND itself and 1 (forgot those two first time round :s). - Mar 20th 2009, 08:13 PMmatheagle