2^2 + 5^2

29

Explanation (brief): 2^2 = 4 and 5^2 = 25, so 4 + 25 = 29. Note: 29 is a prime number and, since 29 = 2^2 + 5^2, it’s a case of a prime ≡ 1 (mod 4) being expressible as a sum of two squares.