lets find the factors to all the numbers between 140 and 150

also notice that the numbers that have exactly 2 prime dividers have 4 factors

141 = 1*3*47

has 4 factors: 1,3,47 and 141

142 = 1*2*71

has 4 factors: 1,2,71 and 142

143 = 1*11*47

has 4 factors: 1,11,47 and 143

144 = 1*2*2*2*2*3*3

has more than 4 factors:1,2,4,6,8,9,12,16...

145 = 1*5*29

has 4 factors: 1,5,29,145

146 = 1*2*73

has 4 factors: 1,2,73 and 146

147 = 1*3*7*7

has more than 4 factors

148 = 1*2*2*37

has more than 4 factors

149 = 1*49

has less than 2 factors: 1 and 149

the numbers 141, 142, 143, 145 and 146 have only 4 factors.