561561561 has 24 divisors (see below), whose sum is σ = 936939744. Its totient is φ = 320319360.

The previous prime is 561561509. The next prime is 561561599. The reversal of 561561561 is 165165165.

It is not a de Polignac number, because 561561561 - 2⁷ = 561561433 is a prime.

561561561 is a modest number, since divided by 561561 gives 561 as remainder.

It is not an unprimeable number, because it can be changed into a prime (561561061) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 165151 + ... + 168516.

It is an arithmetic number, because the mean of its divisors is an integer number (39039156).

Almost surely, 2^561561561 is an apocalyptic number.

561561561 is a gapful number since it is divisible by the number (51) formed by its first and last digit.

It is an amenable number.

561561561 is a deficient number, since it is larger than the sum of its proper divisors (375378183).

561561561 is a wasteful number, since it uses less digits than its factorization.

561561561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333701 (or 333698 counting only the distinct ones).

The product of its digits is 27000, while the sum is 36.

The square root of 561561561 is about 23697.2901615353. The cubic root of 561561561 is about 825.0224963563.

It can be divided in two parts, 5615 and 61561, that added together give a palindrome (67176).

The spelling of 561561561 in words is "five hundred sixty-one million, five hundred sixty-one thousand, five hundred sixty-one".