397
This number is a prime.
The Carillon Residences North Tower in Miami Beach is 397 feet tall.
Conjectured to be the largest prime that can be represented uniquely as the sum of three positive squares (3^2 + 8^2 + 18^2). [Noe]
The prime that splits into a prime pair (3, 97) with sum one
hundred and minimal product (3*97=291). Note
that the sum-product concatenation 100291 is prime, and
that 397 is a left-truncatable prime, just like its
counterpart prime 5347 that splits into two complementary
primes (53, 47) also summing up to a hundred, but with
maximum product (53*47=2491). The reversal of
whose sum-product concatenation however being also prime
(1942001). [Beedassy]
Iranian grandmaster Morteza Mahjoob won 397 (of his
500) chess games to break the Guinness Book World Record for
the most number of simultaneous matches in August 2009.
397 and 401 are the largest pair of consecutive primes that
together have no duplicate digits. [Gaydos]
The smallest non-palindromic balanced prime in base 2. [Nie]