A Colbert number is any prime number with more than decimal digits whose discovery
contributes to the long-sought after proof that is the smallest Sierpiński
number of the second kind. Colbert Numbers are named to honor Stephen T. Colbert.
There are currently five known Colbert numbers, as summarized in the following table.
Colbert number
decimal digits
1521561
3918990
2759677
2357207
2116617
The Seventeen or Bust distributed computing effort is conducting a search for the remaining six Colbert numbers (where indicates the exponent is unknown).