55861 has 4 divisors (see below), whose sum is σ = 60172. Its totient is φ = 51552.
The previous prime is 55849. The next prime is 55871. The reversal of 55861 is 16855.
It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16855 = 5 ⋅3371.
It can be written as a sum of positive squares in 2 ways, for example, as 18225 + 37636 = 135^2 + 194^2 .
It is a cyclic number.
It is not a de Polignac number, because 55861 - 25 = 55829 is a prime.
It is an Ulam number.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (55871) 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, 2136 + ... + 2161.
It is an arithmetic number, because the mean of its divisors is an integer number (15043).
255861 is an apocalyptic number.
It is an amenable number.
55861 is a deficient number, since it is larger than the sum of its proper divisors (4311).
55861 is a wasteful number, since it uses less digits than its factorization.
55861 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 4310.
The product of its digits is 1200, while the sum is 25.
The square root of 55861 is about 236.3493177481. The cubic root of 55861 is about 38.2269429725.
The spelling of 55861 in words is "fifty-five thousand, eight hundred sixty-one".
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