800991 has 12 divisors (see below), whose sum is σ = 1176760. Its totient is φ = 524880.

The previous prime is 800977. The next prime is 800993. The reversal of 800991 is 199008.

It is not a de Polignac number, because 800991 - 2⁵ = 800959 is a prime.

It is an Ulam number.

It is a Duffinian number.

800991 is a lucky number.

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 800991.

It is not an unprimeable number, because it can be changed into a prime (800993) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 181 + ... + 1278.

2⁸⁰⁰⁹⁹¹ is an apocalyptic number.

800991 is a deficient number, since it is larger than the sum of its proper divisors (375769).

800991 is a wasteful number, since it uses less digits than its factorization.

800991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1526 (or 1523 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 27.

The square root of 800991 is about 894.9810053850. The cubic root of 800991 is about 92.8700926431.

Adding to 800991 its reverse (199008), we get a palindrome (999999).

It can be divided in two parts, 8009 and 91, that added together give a square (8100 = 90²).

The spelling of 800991 in words is "eight hundred thousand, nine hundred ninety-one".