55805 has 4 divisors (see below), whose sum is σ = 66972. Its totient is φ = 44640.

The previous prime is 55799. The next prime is 55807. The reversal of 55805 is 50855.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8281 + 47524 = 91^2 + 218^2 .

It is a de Polignac number, because none of the positive numbers 2^k-55805 is a prime.

It is a super-2 number, since 2×55805² = 6228396050, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (55807) 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, 5576 + ... + 5585.

It is an arithmetic number, because the mean of its divisors is an integer number (16743).

2⁵⁵⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

55805 is a deficient number, since it is larger than the sum of its proper divisors (11167).

55805 is a wasteful number, since it uses less digits than its factorization.

55805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11166.

The product of its (nonzero) digits is 1000, while the sum is 23.

The square root of 55805 is about 236.2308193272. The cubic root of 55805 is about 38.2141646803.

Subtracting from 55805 its reverse (50855), we obtain a triangular number (4950 = T₉₉).

The spelling of 55805 in words is "fifty-five thousand, eight hundred five".