prime 27701 and Belfagor 666
 

the prime 27701 has this property

in base 2 it is 110110000110101, which in base ten is a prime (i mean 110110000110101 is prime)
110110000110101 in base ten converted in base 2 is <mn>11001000010010011111011011100010101101000010101</mn> which in base ten is a prime


the sequence is in oeis


now take 11001000010010011111011011100010101101000010101 in base 2 mod 1763 you get 11001100110 in base 2.
now 11001100110 in base 2 to base 16 is 666!!!