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The number 81 is an integer that is the square of 9 (since \(9 \times 9 = 81\)). It belongs to various mathematical categories, including being recognized as a composite number, as it has factors other than 1 and itself (specifically, 1, 3, 9, 27, and 81).

Ancestors (6)

  1. Integers
  2. Numbers
  3. Arithmetic
  4. Fields of mathematics
  5. Mathematics
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