This number is a prime.
Just showing those entries submitted by 'Rivera': (Click here to show all)
1000000087 remains prime after appending and inserting the digit X in all possible positions at the same time: X1X0X0X0X0X0X0X0X8X7X. This is valid for X=3 and for X=9, producing the following two primes 313030303030303038373 and 919090909090909098979. [Rivera]