The vigesimal or base 20 numeral system is based on twenty (in the same way in which the decimal numeral system is based on ten).
base 29
base 29 is a positional numeral system with twenty-nine as its base. It uses 29 different digits for representing numbers. The digits for base 29 could be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, and s.