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{{Infobox |
{{Infobox |
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|title = 31 |
|title = 31 |
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− | |image = 31.png |
+ | |image = 31-D.png |
|imagewidth = 200 |
|imagewidth = 200 |
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|roman-number = XXXI |
|roman-number = XXXI |
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|ordinal-number = thirty first |
|ordinal-number = thirty first |
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+ | |cardinal-number = thirty-one |
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− | |previous = [[29|<font color="white">29</font>]] |
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+ | |standard-form = 3.1{{E|1}} |
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⚫ | |next = |
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+ | |Base-2 Form = 11111 |
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+ | |Base-8 Form = 37 |
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+ | |Base-16 Form = 1F |
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+ | |previous = 29 |
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⚫ | |||
+ | |||
+ | It is also the second pi-prime (First is [[3]]). |
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+ | |||
==Proofs== |
==Proofs== |
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+ | *{{Divisibility number|Yes|1.}} |
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− | *1 can divide 31 |
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+ | *{{Divisibility number|No|2-30.}} |
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− | *2 cannot |
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+ | *{{Divisibility number|Yes|31.}} |
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− | *3 cannot |
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+ | |||
− | *4 - 28 cannot |
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+ | ==As an Exponent of Mersenne Number== |
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− | *29 cannot |
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+ | 2<sup>31</sup> - 1, which is the number 2,147,483,647, is a prime number. It is the 8th Mersenne Prime. |
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− | *30 also cannot |
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+ | |||
− | *31 can divide 31 |
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+ | ==Relationship with other odd numbers== |
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+ | ===The numbers before=== |
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+ | *The previous odd number, 29, is a prime number. |
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+ | **There are no odd numbers between 29 and 31. As a result, they are twin primes. |
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+ | *Before 29, the previous two odd numbers are 25 and 27. 25 is a square number, being 5<sup>2</sup> = 25. 27 is a cube number, being 3<sup>3</sup> = 27. |
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+ | *The prime number previous to 29 is 23. |
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+ | ===The numbers after=== |
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+ | *The next odd number, 33, is '''not''' a prime number. It is divisible by 3 and 11. |
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+ | *The next odd number, 35, is also '''not''' a prime number. It is divisible by 5 and 7. |
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+ | *37, the odd number following 35, is a prime number. |
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+ | **31 and 37 are six numbers apart; therefore, they are sexy primes. |
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+ | |||
+ | {{Navbox primes}} |
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+ | [[Category:Prime numbers from 1-100]] |
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+ | [[Category:Prime Numbers]] |
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+ | [[Category:2-Digit Prime Numbers]] |
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+ | [[Category:Twin Primes]] |
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+ | [[Category:Circular Primes]] |
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+ | [[Category:Sexy Primes]] |
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+ | [[Category:Chen Primes]] |
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+ | [[Category:Russian-doll primes]] |
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+ | [[Category:Multiplicative Persistence 1]] |
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+ | [[Category:Pi-Primes]] |
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+ | [[Category:Mersenne Primes]] |
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+ | [[Category:Primes of the Form Floor]] |
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+ | [[Category:Iccanobif Primes]] |
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+ | [[Category:Emirps]] |
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+ | [[Category:Right-truncatable Primes]] |
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+ | [[Category:Super Primes]] |
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+ | [[Category:Centered Triangular Primes]] |
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+ | [[Category:Centered Decagonal Primes]] |
Latest revision as of 14:24, 29 November 2023
31 is a prime number from 1-100. 31 has 2 factors, 1 and 31. It is said to be a number wherein when digits are added together, they make a composite number. It is the eleventh prime number, and the eleventh prime number from 1-100.
It is also the second pi-prime (First is 3).
Proofs
As an Exponent of Mersenne Number
231 - 1, which is the number 2,147,483,647, is a prime number. It is the 8th Mersenne Prime.
Relationship with other odd numbers
The numbers before
- The previous odd number, 29, is a prime number.
- There are no odd numbers between 29 and 31. As a result, they are twin primes.
- Before 29, the previous two odd numbers are 25 and 27. 25 is a square number, being 52 = 25. 27 is a cube number, being 33 = 27.
- The prime number previous to 29 is 23.
The numbers after
- The next odd number, 33, is not a prime number. It is divisible by 3 and 11.
- The next odd number, 35, is also not a prime number. It is divisible by 5 and 7.
- 37, the odd number following 35, is a prime number.
- 31 and 37 are six numbers apart; therefore, they are sexy primes.