561891 has 8 divisors (see below), whose sum is σ = 817344. Its totient is φ = 340520.

The previous prime is 561839. The next prime is 561907. The reversal of 561891 is 198165.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 561891 - 2¹³ = 553699 is a prime.

561891 is a modest number, since divided by 891 gives 561 as remainder.

It is not an unprimeable number, because it can be changed into a prime (561091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8481 + ... + 8546.

It is an arithmetic number, because the mean of its divisors is an integer number (102168).

2⁵⁶¹⁸⁹¹ is an apocalyptic number.

561891 is a deficient number, since it is larger than the sum of its proper divisors (255453).

561891 is a wasteful number, since it uses less digits than its factorization.

561891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17041.

The product of its digits is 2160, while the sum is 30.

The square root of 561891 is about 749.5938900498. The cubic root of 561891 is about 82.5183797434.

The spelling of 561891 in words is "five hundred sixty-one thousand, eight hundred ninety-one".