smc

Since $A-B$ and $A+B$ must have the same parity, and since there is only one even prime number, it follows that $A-B$ and $A+B$ are both odd. Thus one of $A,B$ is odd and the other even. Since $A+B>A>A-B>2$, it follows that $A$ (as a prime greater than $2$) is odd. Thus $B=2$, and $A-2,A,A+2$ are consecutive odd primes. At least one of $A-2,A,A+2$ is divisible by $3$, from which it follows that $A-2=3$ and $A=5$. The sum of these numbers is thus $17$, a prime, so the answer is $\boxed{\mathrm{prime}}$.