55999 has 4 divisors (see below), whose sum is σ = 57960.
Its totient is φ = 54040.
The previous prime is 55997. The next prime is 56003. The reversal of 55999 is 99955.
It is a happy number.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 99955 = 5 ⋅19991.
It is a cyclic number.
It is not a de Polignac number, because 55999 - 21 = 55997 is a prime.
It is a Duffinian number.
55999 is a modest number, since divided by 999 gives 55 as remainder.
It is a plaindrome in base 10.
It is a zygodrome in base 10.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (55997) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 937 + ... + 994.
It is an arithmetic number, because the mean of its divisors is an integer number (14490).
255999 is an apocalyptic number.
55999 is a deficient number, since it is larger than the sum of its proper divisors (1961).
55999 is a wasteful number, since it uses less digits than its factorization.
55999 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1960.
The product of its digits is 18225, while the sum is 37.
The square root of 55999 is about 236.6410784289.
The cubic root of 55999 is about 38.2583959242.
Subtracting 55999 from its reverse (99955), we obtain a triangular number (43956 = T296).
It can be divided in two parts, 55 and 999, that multiplied together give a palindrome (54945).
The spelling of 55999 in words is "fifty-five thousand, nine hundred ninety-nine".