845991 has 8 divisors (see below), whose sum is σ = 1253360. Its totient is φ = 563976.

The previous prime is 845989. The next prime is 846037. The reversal of 845991 is 199548.

It is not a de Polignac number, because 845991 - 2¹ = 845989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (845921) 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, 15640 + ... + 15693.

It is an arithmetic number, because the mean of its divisors is an integer number (156670).

2⁸⁴⁵⁹⁹¹ is an apocalyptic number.

845991 is a deficient number, since it is larger than the sum of its proper divisors (407369).

845991 is a wasteful number, since it uses less digits than its factorization.

845991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31342 (or 31336 counting only the distinct ones).

The product of its digits is 12960, while the sum is 36.

The square root of 845991 is about 919.7776905318. Note that the first 3 decimals coincide. The cubic root of 845991 is about 94.5776635430.

The spelling of 845991 in words is "eight hundred forty-five thousand, nine hundred ninety-one".