Is 121 a Perfect Square? Yes — √121 = 11

Perfect Square Checker

Use the checker above to determine whether any non-negative integer is a perfect square. A perfect square is a non-negative integer that can be written as the product of an integer with itself: n = k² for some integer k. The first perfect squares are 0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100, ...

Step-by-Step: Why 121 Is a Perfect Square

1. Compute √121:
   √121 = 11 (an integer).
2. Verify by squaring:
   11 × 11 = 121  ✓
3. Prime factorization check:
   121 = 112
   All exponents are even ⇒ 121 is a perfect square.

√121 = 11

⚡ Why this matters: perfect squares are the only positive integers with an odd number of divisors. 121 has 3 divisors — {1, 11, 121} — an odd count, confirming 121 is a perfect square. See all divisors of 121.

What Is a Perfect Square?

A perfect square is a non-negative integer that is the square of an integer:

n is a perfect square  ⇔  n = k²,  k ∈ ℤ_≥0

Equivalently, n is a perfect square if and only if √n is an integer. Geometrically, you can arrange n identical unit squares into a square grid only if n is a perfect square.

Prime-factorization rule: n is a perfect square iff every prime in the prime factorization of n appears with an even exponent. For example, 144 = 2⁴ × 3² (both even) is a perfect square; 72 = 2³ × 3² has an odd exponent on 2, so it is not.

Nearby Examples

Related Operations

• Square Root of 121 — decimal value with Babylonian Method
• What is 121 Squared? — compute n²

References

• [1] Square number (Wikipedia)
• [2] Square Number (Wolfram MathWorld)

Popular Perfect-Square Checks

Common ‘Is N a perfect square?’ queries — click any to see the step-by-step verdict: