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19 is a prime number from 1-100. 19 has 2 factors, 1 and 19. It is said to be the last number ranging from 1-100 that ends with teen, and after this number, by age you are already 20 years old, so you are not a teenager anymore. It is the eighth prime number, and the eighth prime number from 1-100.

It is also the smallest prime number that itself reversed is not prime.

Proofs[]

  • Yes — 19 can be divided by 1.
  • No — 19 cannot be divided by 2-18.
  • Yes — 19 can be divided by 19.
  • Therefore it has 2 factors

As an Exponent of Mersenne Number[]

219 - 1, which is the number 524,287, is a prime number. It is the 7th Mersenne Prime.

​Relationship with other odd numbers[]

The numbers before[]

  • The previous odd number, 17, is a prime number.
    • There are no odd numbers between 17 and 19. As a result, they are twin primes.
  • The odd number previous to 17 is 15. 15 is not a prime number. It is divisible by 3 and 5.
  • The odd number previous to 15 is 13. 13 is a prime number.
    • 13 and 19 are six numbers apart; therefore, they are sexy primes.

The numbers after[]

  • The next odd number, 21, is not a prime number. It is divisible by 3 and 7.
  • 23, the odd number following 21, is a prime number.
    • 19 and 23 are four numbers apart; therefore, they are cousin primes.
  • 25, the odd number following 23, is not a prime number. It is a square number, being 52 = 25.
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