For example, 256 is a prime productive number since , , and are all prime numbers.
There are only 208 productive numbers below , the largest being 8220001387336.
By definition, each productive number is one less than a prime number, so they are all even (except for 1) and do not end with the digit '4' (except for 4 itself).
The first prime productive numbers are 1, 2, 4, 6, 12, 16, 22, 28, 36, 52, 58, 66, 82, 106, 112, 136, 166, 178, 256, 306, 336, 352, 448 more terms