# 1992

This number is a composite.

1992 = 8 x 3 x 83. The *only* other two years in the period
1000 to 1999 to share the structure of "*a* x *b* x '*ab*'" (where '*ab*' is prime and
the concatenation of the factors *a* and *b*) are 1316 = 4 x 7 x 47 and 1533 = 7 x 3 x 73. [Trotter]

If you separate the digits of 1992 like 199 2, you have two primes. Note that 199 is the largest prime less than 2 hundred. Separation in the middle gives us 19 92, and 19 turned upside down along with 92 reversed are prime. [Trotter]

Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell