561728861 has 2 divisors, whose sum is σ = 561728862. Its totient is φ = 561728860.

The previous prime is 561728851. The next prime is 561728879. The reversal of 561728861 is 168827165.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 560505625 + 1223236 = 23675^2 + 1106^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561728861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (561728831) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 280864430 + 280864431.

It is an arithmetic number, because the mean of its divisors is an integer number (280864431).

Almost surely, 2^561728861 is an apocalyptic number.

It is an amenable number.

561728861 is a deficient number, since it is larger than the sum of its proper divisors (1).

561728861 is an equidigital number, since it uses as much as digits as its factorization.

561728861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 161280, while the sum is 44.

The square root of 561728861 is about 23700.8198381406. The cubic root of 561728861 is about 825.1044182497.

The spelling of 561728861 in words is "five hundred sixty-one million, seven hundred twenty-eight thousand, eight hundred sixty-one".