Is 81 a Prime Number or Composite Number [Why & Why not Detailed Guide]

Last Updated: August 26, 2024

Is 81 a Prime Number or Composite Number [Why & Why not Detailed Guide]

Is 81 a Prime Number or Composite Number

Is 81 a Prime Number?

No: 81 is not a Prime Number.

Why No: 81 is not a prime number because it does not meet the prime criteria of having exactly two distinct positive divisors: 1 and itself. See Prime number checker

Is 81 a Prime Number

Is 81 a Composite Number?

Yes: 88 is a Composite Number.

Why Yes: 81 is a composite number because it has more than two distinct positive divisors. It is divisible by 1, 3, 9, 27, and itself (81).

Is 81 a Composite Number

Problem Statements

Property Answer
Is 81 a prime number? No
Is 81 a composite number? Yes
Is 81 a perfect square? Yes
Factors of 81 1, 3, 9, 27, 81
Multiples of 81 81, 162, 243, 324, 405, 486, 567, 648, 729, 810
Cube Root of 81 4.327
Square of 81 6561
Square Root of 81 9
Is 81 a Perfect Cube? No
Is 81 an Irrational number No
Is 81 a Rational number Yes
Is 81 a Real number Yes
Is 81 an Integer Yes
Is 81 a Natural number Yes
Is 81 a Whole number Yes
Is 81 an Even or odd number Yes (81 is an odd number)
Is 81 an Ordinal number Yes
Is 81 a Complex number Yes (as all real numbers are also complex numbers)

What are the factors of 81?

The factors of 81 are 1, 3, 9, 27, and 81. 81 is not a prime number because it is divisible by numbers other than 1 and itself, demonstrating it has more than two factors. This clarity confirms that it is a composite number, not a prime number.

What Kind of Number is 81?

  • 81: A Composite Number with Unique Divisors
  • The Oddity of 81: Distinguishing It from Even Numbers
  • 81’s Significance: Beyond Just a Number
  • 81 as a Natural and Positive Integer
  • 81 in Mathematical Dialogue: Composite Over Prime
  • The Rationality and Wholeness of 81
  • 81: An Integral Part of Mathematical Discussions.

Nearest Prime Number of 81

The nearest prime numbers to 81 are 79 and 83. 79 is the closest prime number less than 81, and 83 is the closest prime number greater than 81.

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Practice Test

Which of the following describes 81 accurately?

81 is a prime number

81 is a composite number

81 is a perfect square

81 is a rational number

of 10

What can be said about the number 81 if it can be divided evenly by 3?

It is a prime number

It is a composite number

It is a fraction

It is an irrational number

of 10

Which of these is not a factor of 81?

1

9

12

27

of 10

Which of these statements is true about 81?

81 is a perfect square

81 is a prime number

81 is a prime factor

 81 is a fraction

of 10

What type of number is 81 if it is divisible by both 9 and 27?

Prime

Composite

Real

Imaginary

of 10

What property confirms that 81 is not a prime number?

 It is divisible by 3

It ends in 1

It is an odd number

 It is greater than 50

of 10

Which of the following statements is true for 81?

It is a prime number

It can be expressed as 9 × 9

 It is less than 100

 It is divisible by 2

of 10

Which of these is a property of composite numbers like 81?

They are divisible by more than two numbers

They are only divisible by 1 and themselves

 They are always even

They are always prime

of 10

What type of number is 81 if it is divisible by 3 and 9?

 Prime

Composite

Rational

Whole

of 10

Which statement is accurate for the number 81?

 It has exactly two factors

 It is a prime number

It is a composite number with multiple factors

It cannot be divided by 1

of 10

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