561666040 has 64 divisors (see below), whose sum is σ = 1383348960. Its totient is φ = 203973120.

The previous prime is 561666023. The next prime is 561666041. The reversal of 561666040 is 40666165.

It is a junction number, because it is equal to n+sod(n) for n = 561665987 and 561666005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (561666041) 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 in 15 ways as a sum of consecutive naturals, for example, 22867 + ... + 40573.

Almost surely, 2^561666040 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 561666040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (691674480).

561666040 is an abundant number, since it is smaller than the sum of its proper divisors (821682920).

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

561666040 is a wasteful number, since it uses less digits than its factorization.

561666040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17792 (or 17788 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 34.

The square root of 561666040 is about 23699.4945093772. The cubic root of 561666040 is about 825.0736585596.

The spelling of 561666040 in words is "five hundred sixty-one million, six hundred sixty-six thousand, forty".