561666666 has 64 divisors (see below), whose sum is σ = 1259919360. Its totient is φ = 165480960.

The previous prime is 561666661. The next prime is 561666713. The reversal of 561666666 is 666666165.

561666666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

561666666 is a modest number, since divided by 66666 gives 5616 as remainder.

It is not an unprimeable number, because it can be changed into a prime (561666661) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 376975 + ... + 378461.

It is an arithmetic number, because the mean of its divisors is an integer number (19686240).

Almost surely, 2^561666666 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561666666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (629959680).

561666666 is an abundant number, since it is smaller than the sum of its proper divisors (698252694).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

561666666 is a wasteful number, since it uses less digits than its factorization.

561666666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1659.

The product of its digits is 1399680, while the sum is 48.

The square root of 561666666 is about 23699.5077164063. The cubic root of 561666666 is about 825.0739650857.

The spelling of 561666666 in words is "five hundred sixty-one million, six hundred sixty-six thousand, six hundred sixty-six".