106 (one hundred [and] six) is the natural number following 105 and preceding 107. 106 is the thirty-first distinct biprime and the fifteenth of the form (2.q). The aliquot sum of 106 is 56 within the aliquot sequence (106,56,64,63,41,1) 106 being the eleventh composite number in the 41-aliquot tree. 106 is a centered pentagonal number, a centered heptagonal number, and a regular 19-gonal number. There are 106 distinct mathematical trees with ten vertices.