31 is the number of regular polygons with an odd number of sides that are known to be constructible with compass and straightedge. 31 has 2 factors 1 and 31. 100 Prime Number Chart Zazzle Prime Numbers Number Chart Free Printable Numbers Is 31 a perfect number. . Prime numbers are the numbers greater than 1 that have exactly two factors 1 and the number itself. A prime number is a natural number greater than 1 that is not a product of two smaller natural numbers. 31 is the third Mersenne prime 2 5. Gupta 31 is the largest primorial prime less than the next prime squared ie 5 1 235 1 31 7 2 49. Is 31 a composite number. 47 rows A prime number is a positive integer excluding 1 with no divisors other than 1 and itself. Hence we must say that 31 is a prime number. Is 31 a perfect square. In other words 31 is only divided by 1 or by itself. Check 31 Prime Number Or Not. So it is a prime number.