Which of the following is not a prime number?

Given data

• Options: 97, 121, 83, 89

Concept / Approach

• A prime has exactly two distinct positive divisors: 1 and itself.
• 1221? No; check each option up to its square root. For a perfect square n = p^2 with p > 1, n is never prime.

Step-by-step checks

121 = 11 × 11 → composite97, 83, 89: not divisible by any prime ≤ 10 (2, 3, 5, 7) → each is prime

Common pitfalls

• Confusing a large odd number with being prime. Always test by small primes up to √n.

Final Answer

The non-prime is 121.