561665243 has 4 divisors (see below), whose sum is σ = 581033040. Its totient is φ = 542297448.

The previous prime is 561665231. The next prime is 561665281. The reversal of 561665243 is 342566165.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 561665243 - 2¹⁰ = 561664219 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 561665197 and 561665206.

It is not an unprimeable number, because it can be changed into a prime (561665743) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9683855 + ... + 9683912.

It is an arithmetic number, because the mean of its divisors is an integer number (145258260).

Almost surely, 2^561665243 is an apocalyptic number.

561665243 is a deficient number, since it is larger than the sum of its proper divisors (19367797).

561665243 is a wasteful number, since it uses less digits than its factorization.

561665243 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19367796.

The product of its digits is 129600, while the sum is 38.

The square root of 561665243 is about 23699.4776946666. The cubic root of 561665243 is about 825.0732683015.

The spelling of 561665243 in words is "five hundred sixty-one million, six hundred sixty-five thousand, two hundred forty-three".