55 (number)

55 (fifty-five) is the natural number following 54 and preceding 56.

Mathematics:

• 55 is an odd number.
• 55 is a composite number, its divisors being 1, 5, 11, and 55.
• 55 is a triangular number.
• 55 is a Fibonacci number. Specifically, it is the 10th Fibonacci number.
• 55 is a Motzkin number.
• 55 is a repdigit in base 10.
• 55 is the sum of the first 5 triangular numbers.
• 55 is the largest number that is the sum of consecutive primes starting at 5: 5 + 7 + 11 + 13 + 17 = 53. However, 55 can be represented as 3 + 5 + 7 + 11 + 13 + 14 = 53.

Other Fields:

• In the United States, 55 is a common speed limit (miles per hour).
• Various cultural references exist involving the number 55.