6446 = 2 x 11 x 293. It is a palindrome with exactly three distinct prime factors (A046329 and A046393).
6446 is a sphenic number with semiprime digits (A111494) and with even digits (A062287).
6446 is a palindrome that is the sum of consecutive squares (A180436).
6446 is a palindrome not divisible by any of its digits (A082947) nor by the sum of its digits (A082948).
6446 is a palindrome of length greater than 1 in the decimal expansion of pi (A068046).
6446 is 24536 in base 7.
Source: On-Line Encyclopedia of Integer Sequences