561689 has 4 divisors (see below), whose sum is σ = 579840. Its totient is φ = 543540.

The previous prime is 561667. The next prime is 561703. The reversal of 561689 is 986165.

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, and also an emirpimes, since its reverse is a distinct semiprime: 986165 = 5 ⋅197233.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-561689 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (561389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9029 + ... + 9090.

It is an arithmetic number, because the mean of its divisors is an integer number (144960).

2⁵⁶¹⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

561689 is a deficient number, since it is larger than the sum of its proper divisors (18151).

561689 is a wasteful number, since it uses less digits than its factorization.

561689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18150.

The product of its digits is 12960, while the sum is 35.

The square root of 561689 is about 749.4591383124. The cubic root of 561689 is about 82.5084900966.

The spelling of 561689 in words is "five hundred sixty-one thousand, six hundred eighty-nine".