A prime number is any positive integer (excluding 1) having no integral factors other than itself and unity, e.g. 2, 3, 5, 7, or 11. The lowest prime number is 2. The highest known prime number is 244497-1 (a number of 13,395 digits), discovered of Apr. 8, 1979, after a 2-month-long run on a Cray One Computer at the University of Calif's Lawrence Livermore Labortory by Harry Nelson 47, and David Slowinski, 25.
A number is said to be perfect if it is equal to the sum of its divisors other than itself, e.g. 1+2+4+7+14=28. The lowest perfect number is 6 (1+2+3). The highest know, and the 26th so far discovered, is (244497-1) × 244496. It is a consequence of the highest know prime (above).