• 54 can be written using four 4's:
54 has 8 divisors (see below), whose sum is σ = 120. Its totient is φ = 18.
The previous prime is 53. The next prime is 59. The reversal of 54 is 45.
54 is nontrivially palindromic in base 8.
54 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.
54 is an admirable number.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is a Leyland number of the form 33 + 33.
It is an alternating number because its digits alternate between odd and even.
Its product of digits (20) is a multiple of the sum of its prime divisors (5).
It is a Curzon number.
54 is a nontrivial repdigit in base 8.
It is a plaindrome in base 8, base 11, base 12, base 14, base 15 and base 16.
It is a nialpdrome in base 3, base 8, base 9, base 10 and base 13.
It is a zygodrome in base 8.
It is a congruent number.
It is a panconsummate number.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17 + 18 + 19.
It is an arithmetic number, because the mean of its divisors is an integer number (15).
It is a practical number, because each smaller number is the sum of distinct divisors of 54, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (60).
54 is an abundant number, since it is smaller than the sum of its proper divisors (66).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
54 is a wasteful number, since it uses less digits than its factorization.
54 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 11 (or 5 counting only the distinct ones).
The product of its digits is 20, while the sum is 9.
The square root of 54 is about 7.3484692283. The cubic root of 54 is about 3.7797631497.
Adding to 54 its reverse (45), we get a palindrome (99).
The spelling of 54 in words is "fifty-four", and thus it is an aban number and an eban number.
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