Binary: 110111

Septimal (base 7): 106

Octal: 67

Hexadecimal: 37

Base 24: 27

55 = 5 × 11

55 has 4 divisors: 1, 5, 11, 55

Sum of all divisors other than 55: 17

Difference of 2 squares: 55 = 8² - 3² = 28² - 27²

55 is a Fibonacci number

55 is a triangular number
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The next triangular is: 66

55 is a heptagonal number

55 is a palindromic number in decimal system

The 55th prime number is: 257

Previous prime number: 53 — Next prime number: 59