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.
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.