27616 is a member of OEIS A358782: number of regions formed when every pair of n points, placed at the vertices of a regular n-gon, are connected by a circle and where the points lie at the ends of the circle's diameter, here n=21. See attached screenshot for case of n=20.

Initial members are:

1, 7, 12, 66, 85, 281, 264, 802, 821, 1893, 1740, 3810, 3725, 6871, 6448, 11748, 11125, 18317, 17160, 27616, 26797, 40067, 37176, 56826, 54653, 77707, 74788, 103734, 101041, 136835, 131744, 176584, 172109, 223931, 216900, 281090, 273829, 348583, 337480, 425950, 416641

27616 is a katadrome in base 13 (c754) because its digits are strictly decreasing.

27616 can be rendered as a digit equation as follows:

-2 + 7 = 6 - 1 ^ 6