891561 has 8 divisors (see below), whose sum is σ = 1296864. Its totient is φ = 540320.

The previous prime is 891559. The next prime is 891563. The reversal of 891561 is 165198.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (891559) and next prime (891563).

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

It is not a de Polignac number, because 891561 - 2¹ = 891559 is a prime.

It is not an unprimeable number, because it can be changed into a prime (891563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13476 + ... + 13541.

It is an arithmetic number, because the mean of its divisors is an integer number (162108).

2⁸⁹¹⁵⁶¹ is an apocalyptic number.

It is an amenable number.

891561 is a deficient number, since it is larger than the sum of its proper divisors (405303).

891561 is a wasteful number, since it uses less digits than its factorization.

891561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27031.

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

The square root of 891561 is about 944.2250790993. The cubic root of 891561 is about 96.2462212493.

The spelling of 891561 in words is "eight hundred ninety-one thousand, five hundred sixty-one".