217

217 = 7 x 31.

217 is the ninth centered hexagonal (hex) number.

47 and 89 are primes, as is their concatenation: 4789. Inserting 0 between them transforms the prime into a power: 47089 = 217².

217 is 1001 in base 6 and 161 in base 12.

217 is the telephone area code covering much of central Illinois.

Source: Prime Curios!