561506581 has 4 divisors (see below), whose sum is σ = 561710700. Its totient is φ = 561302464.

The previous prime is 561506573. The next prime is 561506591. The reversal of 561506581 is 185605165.

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 482900625 + 78605956 = 21975^2 + 8866^2 .

It is a cyclic number.

It is not a de Polignac number, because 561506581 - 2³ = 561506573 is a prime.

It is a super-2 number, since 2×561506581² = 630579281012619122, 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 561506581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561506501) 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, 97876 + ... + 103453.

It is an arithmetic number, because the mean of its divisors is an integer number (140427675).

Almost surely, 2^561506581 is an apocalyptic number.

It is an amenable number.

561506581 is a deficient number, since it is larger than the sum of its proper divisors (204119).

561506581 is a wasteful number, since it uses less digits than its factorization.

561506581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204118.

The product of its (nonzero) digits is 36000, while the sum is 37.

The square root of 561506581 is about 23696.1300848894. The cubic root of 561506581 is about 824.9955707139.

The spelling of 561506581 in words is "five hundred sixty-one million, five hundred six thousand, five hundred eighty-one".