538

538 = 2 x 269.

538 has a representation as a sum of two squares: 538 = 3² + 23².

538 is the 10th open meandric number: 1, 1, 2, 3, 8, 14, 42, 81, 262, 538, 1828, . . .

538 is a number such that the sum of its odd digits equals the sum of its even digits: 5 + 3 = 8.

The Electoral College consists of 538 popularly elected representatives who formally select the President and the Vice President of the United States.

Source: WolframAlpha