by mithunsam Sat Aug 27, 2011 10:25 pm
This question can be solved in many ways. One simple way is to figure out whether we could take any common factor out.
2222^5555 + 5555^2222 = (2*1111)^5555 + (5*1111)^2222
= (2^5555 * 1111^5555) + (5^2222 * 1111^2222)
= 1111^2222(2^5555 * 1111^3333 + 5^2222) => Not a prime