561556561 has 4 divisors (see below), whose sum is σ = 565655652. Its totient is φ = 557457472.

The previous prime is 561556559. The next prime is 561556579. The reversal of 561556561 is 165655165.

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 124746561 + 436810000 = 11169^2 + 20900^2 .

It is a cyclic number.

It is not a de Polignac number, because 561556561 - 2¹ = 561556559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (561556861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2049340 + ... + 2049613.

It is an arithmetic number, because the mean of its divisors is an integer number (141413913).

Almost surely, 2^561556561 is an apocalyptic number.

It is an amenable number.

561556561 is a deficient number, since it is larger than the sum of its proper divisors (4099091).

561556561 is a wasteful number, since it uses less digits than its factorization.

561556561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4099090.

The product of its digits is 135000, while the sum is 40.

The square root of 561556561 is about 23697.1846640060. The cubic root of 561556561 is about 825.0200477528.

The spelling of 561556561 in words is "five hundred sixty-one million, five hundred fifty-six thousand, five hundred sixty-one".