1719

1719 = 3 x 3 x 191.

1719 is the concatenation of the seventh and eighth primes (A045533 and A007795), a pair of twin primes, or two consecutive odd numbers (A032607).

1719 is the largest integer that cannot be written as the sum of squares of integers larger than 16 (A193018).

1719 is the sum of 11 non-zero 6th powers (A003367).

1719 is the smallest number expressible as a sum of 9 cubes (including 0) in 43 ways (A214725).

Source: On-Line Encyclopedia of Integer Sequences