561255561 has 40 divisors (see below), whose sum is σ = 892675080. Its totient is φ = 350203392.

The previous prime is 561255559. The next prime is 561255577. The reversal of 561255561 is 165552165.

It can be written as a sum of positive squares in 4 ways, for example, as 217857600 + 343397961 = 14760^2 + 18531^2 .

It is not a de Polignac number, because 561255561 - 2¹ = 561255559 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (561255521) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 270235 + ... + 272303.

It is an arithmetic number, because the mean of its divisors is an integer number (22316877).

Almost surely, 2^561255561 is an apocalyptic number.

561255561 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

561255561 is a deficient number, since it is larger than the sum of its proper divisors (331419519).

561255561 is a wasteful number, since it uses less digits than its factorization.

561255561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2295 (or 2286 counting only the distinct ones).

The product of its digits is 45000, while the sum is 36.

The square root of 561255561 is about 23690.8328473273. The cubic root of 561255561 is about 824.8726150428.

The spelling of 561255561 in words is "five hundred sixty-one million, two hundred fifty-five thousand, five hundred sixty-one".