561805 has 4 divisors (see below), whose sum is σ = 674172. Its totient is φ = 449440.

The previous prime is 561797. The next prime is 561809. The reversal of 561805 is 508165.

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 114244 + 447561 = 338^2 + 669^2 .

It is not a de Polignac number, because 561805 - 2³ = 561797 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 561805.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561809) 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, 56176 + ... + 56185.

It is an arithmetic number, because the mean of its divisors is an integer number (168543).

2⁵⁶¹⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

561805 is a deficient number, since it is larger than the sum of its proper divisors (112367).

561805 is a wasteful number, since it uses less digits than its factorization.

561805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 112366.

The product of its (nonzero) digits is 1200, while the sum is 25.

The square root of 561805 is about 749.5365234597. The cubic root of 561805 is about 82.5141695895.

It can be divided in two parts, 56180 and 5, that multiplied together give a square (280900 = 530²).

The spelling of 561805 in words is "five hundred sixty-one thousand, eight hundred five".