Twenty-seven is a cube of 3: 3³ = 3 × 3 × 3.

Also:

• 27 it is the first composite number not divisible by any of its digits
• 27 is the only positive integer that is 3 times the sum of its digits
• 27 contains the decimal digits 2 and 7, and is the result of adding together the integers from 2 to 7 (2 + 3 + 4 + 5 + 6 + 7 = 27).