# Is 18 a Prime Number?

Is 18 a prime number? Numbers having only 2 factors, i.e. 1 and the number itself are known as prime numbers whereas numbers with more than 2 factors are known as composite. The answer to the question whether 18 is a prime or composite is - * "18 is a composite number."* Now, let us find out how and why is 18 a prime number or a composite number?

**Is 18 a prime number? -**No**Is 18 a composite number? -**Yes**Is 18 a perfect square? -**No**Prime Factors of 18 -**2, 3**Factors of 18 -**1, 2, 3, 6, 9, 18

## Is 18 a Prime Number?

No, 18 is not a prime number. The number 18 is divisible by 1, 2, 3, 6, 9, 18. For a number to be classified as a prime number, it should have exactly two factors. Since 18 has more than two factors, i.e. 1, 2, 3, 6, 9, 18, it is not a prime number.

## Why is 18 not a Prime Number?

To understand whether 18 is composite or prime, it is important to find its factors.

**Factors of 18:** 1, 2, 3, 6, 9, 18

Since 18 has more than 2 factors, we can say that 18 is not a prime number.

## Is 18 a Composite Number?

Yes, since 18 has more than two factors i.e. 1, 2, 3, 6, 9, 18. In other words, 18 is a composite number because 18 has more than 2 factors.

**Problem Statements: **

Is 18 a Prime Number? | No |

Is 18 a Composite Number? | Yes |

Is 18 an Odd Number? | No |

Square Root of 18 | 4.242641 |

Cube Root of 18 | 2.620739 |

Is 18 a Perfect Cube? | No |

Is 18 an Even Number? | Yes |

Is 18 a Perfect Square? | No |

Multiples of 18 | 18, 36, 54, 72, 90, 108, 126, 144, 162, 180 |

Square of 18 | 324 |

**Fun Facts: **

- Prime numbers greater than 5 can be represented in the form of either 6n + 1 or 6n - 1. Example - 71 is a prime number and it can be written as 71 = 6 × 12 - 1
- 1 is neither prime nor composite.
- Euler discovered a polynomial n
^{2}+ n + 41 that produces prime numbers for values of n that lie between 0 and 39 inclusive. It can generate 40 prime numbers for 0 <= n <= 39.

**☛ Also Check: **

- Is 23 a Prime Number? - Yes
- Is 121 a Prime Number? - No
- Is 55 a Prime Number? - No
- Is 5 a Prime Number? - Yes
- Is 77 a Prime Number? - No
- Is 110 a Prime Number? - No
- Is 46 a Prime Number? - No
- Is 817 a Prime Number? - No

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