191

This number is a prime.

Just showing those entries submitted by 'Haga': (Click here to show all)

Multiply the even composites 4*6*8 - 1 and get 191 using 3 terms and 2 multiplications. Do the same + 1 and get 193 -- the first set of twin primes using this process. [Haga]

Zero appears 191 times in the first one thousand primes. [Haga]