211 is a prime number.
211 is the smallest prime such that the sum of its even digits equals the sum of its odd digits.
211 is 111 in base 14.
211 is a centered decagonal number.
211 is the maximum number of regions into which 20 lines divide the plane.
211 is the number of primes that can appear on a 24-hour digital clock starting from 00:00 up to 23:59.
Source: Number Gossip