891999 has 8 divisors (see below), whose sum is σ = 1321520. Its totient is φ = 594648.

The previous prime is 891997. The next prime is 892019. The reversal of 891999 is 999198.

It is not a de Polignac number, because 891999 - 2¹ = 891997 is a prime.

It is a Duffinian number.

891999 is a modest number, since divided by 999 gives 891 as remainder.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 891999.

It is not an unprimeable number, because it can be changed into a prime (891991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16492 + ... + 16545.

It is an arithmetic number, because the mean of its divisors is an integer number (165190).

2⁸⁹¹⁹⁹⁹ is an apocalyptic number.

891999 is a deficient number, since it is larger than the sum of its proper divisors (429521).

891999 is a wasteful number, since it uses less digits than its factorization.

891999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33046 (or 33040 counting only the distinct ones).

The product of its digits is 52488, while the sum is 45.

The square root of 891999 is about 944.4569868448. The cubic root of 891999 is about 96.2619797311.

The spelling of 891999 in words is "eight hundred ninety-one thousand, nine hundred ninety-nine".