54 (number)

54 is a natural number that lies between 53 and 55. It is written in the decimal system as two digits: 5 and 4. It is an even number, since it is divisible by two with no remainder.

In mathematics, 54 can be expressed by prime factorization as 2 × 3 × 3 × 3, or 2 × 3³. Its complete set of divisors is 1, 2, 3, 6, 9, 18, 27, and 54.

Mathematical properties

The sum of its proper divisors (those smaller than the number itself) is 1 + 2 + 3 + 6 + 9 + 18 + 27 = 66. Since 66 is greater than 54, it belongs to the class of numbers called abundant numbers. The sum of the digits in its decimal representation is 5 + 4 = 9, which indicates that both 3 and 9 divide it evenly.

54 is not a prime number, since it has divisors other than 1 and itself. It is not a perfect power, but it equals 2 times 27, where 27 is the cube of 3 (3³).

Geometry

An angle of 54 degrees is related to the regular pentagon and pentagram construction, as 54 is one-quarter of 216, and it is also connected to 108, the interior angle of a regular pentagon (108 = 2 × 54).

Common usage

The number 54 appears in standard counting systems: years, numbering people, measurements, and various classifications. For example, a deck of playing cards has 54 cards when two jokers are added to the standard 52.