This number is a prime.
The square root of 4456321. (The reversal of 4456321 is 1112 squared.)
2111 = 1 + 2^2 + 2^3 + 2^5 + 2^7 + 2^11. The exponents are consecutive primes. [Noe]
The smaller of only two primes less than a googol formed by concatenating in descending order the first n multidigit numbers ending with 1, (case n=2). The other is 41312111 for n=4. [Loungrides]
2111 is the smallest start of a run of five primes obtained by the following procedure: replace each digit of 2111 with the digit's square to obtain a new prime, and up to five primes doing this recursively, i.e., 2111, 4111, 16111, 136111 and 1936111. [Rivera]
2111 is the smallest four-digit prime which remains prime when 2 is added to any of its digits. [Petrov]