75

75 = 3 x 5²

75 is the smallest pandigital number in base 4: 75 is written as 1023 in base 4 and contains all the possible digits.

75 is 55 in base 14.

2⁷⁵ + 75 is a prime number.

Take the "digit sum" 7 + 5 = 12, then continue adding in pairs (as shown below). You reach 75.

7 + 5 = 12

5 + 12 = 17

12 + 17 = 29

17 + 29 = 46

29 + 46 = 75


Messier object M75 is a globular cluster in the constellation Sagittarius.

Source: Number Gossip