812891 has 4 divisors (see below), whose sum is σ = 816312. Its totient is φ = 809472.

The previous prime is 812869. The next prime is 812921. The reversal of 812891 is 198218.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 198218 = 2 ⋅99109.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-812891 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (812191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325 + ... + 1838.

It is an arithmetic number, because the mean of its divisors is an integer number (204078).

2⁸¹²⁸⁹¹ is an apocalyptic number.

812891 is a deficient number, since it is larger than the sum of its proper divisors (3421).

812891 is a wasteful number, since it uses less digits than its factorization.

812891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3420.

The product of its digits is 1152, while the sum is 29.

The square root of 812891 is about 901.6046805557. The cubic root of 812891 is about 93.3277448468.

The spelling of 812891 in words is "eight hundred twelve thousand, eight hundred ninety-one".