605

605 = 5 x 11².

605 has a sum of digits equal to its largest prime factor (11).

605 has a representation as a sum of two squares: 605 = 11² + 22².

605 is a member of the sequence obtained by starting with 1, then repeatedly reversing the digits and adding 2: 1, 3, 5, 7, 9, 11, 13, 33, 35, . . . , 306, 605, 508, . . .


605 is the telephone area code for the state of South Dakota.

Source: What’s Special About This Number?