561581 has 4 divisors (see below), whose sum is σ = 565500. Its totient is φ = 557664.

The previous prime is 561559. The next prime is 561599. The reversal of 561581 is 185165.

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 259081 + 302500 = 509^2 + 550^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561581 is a prime.

It is a super-2 number, since 2×561581² = 630746439122, which contains 22 as substring.

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 561581.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 561581.

It is not an unprimeable number, because it can be changed into a prime (561521) 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, 1736 + ... + 2033.

It is an arithmetic number, because the mean of its divisors is an integer number (141375).

2⁵⁶¹⁵⁸¹ is an apocalyptic number.

It is an amenable number.

561581 is a deficient number, since it is larger than the sum of its proper divisors (3919).

561581 is a wasteful number, since it uses less digits than its factorization.

561581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3918.

The product of its digits is 1200, while the sum is 26.

The square root of 561581 is about 749.3870828884. The cubic root of 561581 is about 82.5032015899.

The spelling of 561581 in words is "five hundred sixty-one thousand, five hundred eighty-one".