55440 has 120 divisors (see below), whose sum is σ = 232128. Its totient is φ = 11520.

The previous prime is 55439. The next prime is 55441. The reversal of 55440 is 4455.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (55439) and next prime (55441).

It is a tau number, because it is divible by the number of its divisors (120).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nialpdrome in base 10.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (55441) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5035 + ... + 5045.

55440 is a highly composite number, because it has more divisors than any smaller number.

55440 is a superabundant number, because it has a larger abundancy index than any smaller number.

2⁵⁵⁴⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 55440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116064).

55440 is an abundant number, since it is smaller than the sum of its proper divisors (176688).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

55440 is a wasteful number, since it uses less digits than its factorization.

55440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37 (or 28 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 18.

The square root of 55440 is about 235.4570024442. The cubic root of 55440 is about 38.1306674366.

Adding to 55440 its reverse (4455), we get a palindrome (59895).

It can be divided in two parts, 5 and 5440, that added together give a palindrome (5445).

The spelling of 55440 in words is "fifty-five thousand, four hundred forty".