561661121 has 4 divisors (see below), whose sum is σ = 641898432. Its totient is φ = 481423812.

The previous prime is 561660997. The next prime is 561661123. The reversal of 561661121 is 121166165.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 561661121 - 2¹⁰ = 561660097 is a prime.

It is not an unprimeable number, because it can be changed into a prime (561661123) 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, 40118645 + ... + 40118658.

It is an arithmetic number, because the mean of its divisors is an integer number (160474608).

Almost surely, 2^561661121 is an apocalyptic number.

It is an amenable number.

561661121 is a deficient number, since it is larger than the sum of its proper divisors (80237311).

561661121 is an equidigital number, since it uses as much as digits as its factorization.

561661121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80237310.

The product of its digits is 2160, while the sum is 29.

The square root of 561661121 is about 23699.3907305652. The cubic root of 561661121 is about 825.0712499223.

The spelling of 561661121 in words is "five hundred sixty-one million, six hundred sixty-one thousand, one hundred twenty-one".