Topic: Prime curious 1111
1111:
The concatenation of the prime number 11 with itself.
1111 equals 112 + 122 + 132 + 142 + 152 + 162. [De Geest]
1111 = 11 x 101 in base 10 and in base 2, where 11 and 101 are both prime in base 10 and base 2. [Shafer]
The sum of the digits of the first 100 primes. [Wilson]