812991 has 16 divisors (see below), whose sum is σ = 1209600. Its totient is φ = 482688.

The previous prime is 812969. The next prime is 813013. The reversal of 812991 is 199218.

It is an interprime number because it is at equal distance from previous prime (812969) and next prime (813013).

It is not a de Polignac number, because 812991 - 2¹⁵ = 780223 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (812921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 550 + ... + 1388.

It is an arithmetic number, because the mean of its divisors is an integer number (75600).

2⁸¹²⁹⁹¹ is an apocalyptic number.

812991 is a deficient number, since it is larger than the sum of its proper divisors (396609).

812991 is a wasteful number, since it uses less digits than its factorization.

812991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878.

The product of its digits is 1296, while the sum is 30.

The square root of 812991 is about 901.6601355278. The cubic root of 812991 is about 93.3315716788.

The spelling of 812991 in words is "eight hundred twelve thousand, nine hundred ninety-one".