primenumber Top-quality integer, per the USDA? One of 25 under 100 (but not 1, 25 or 100) 73 or 173, to mathematicians 3, 5 or 7, but not 9 2 or 3 — but not 4 13 Excellent anaesthetic like 3 perhaps 2 or 3, but not 4 Head anesthesiologist?