820891 has 2 divisors, whose sum is σ = 820892. Its totient is φ = 820890.

The previous prime is 820873. The next prime is 820901. The reversal of 820891 is 198028.

820891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 820891 - 2⁷ = 820763 is a prime.

It is not a weakly prime, because it can be changed into another prime (820691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410445 + 410446.

It is an arithmetic number, because the mean of its divisors is an integer number (410446).

2⁸²⁰⁸⁹¹ is an apocalyptic number.

820891 is a deficient number, since it is larger than the sum of its proper divisors (1).

820891 is an equidigital number, since it uses as much as digits as its factorization.

820891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1152, while the sum is 28.

The square root of 820891 is about 906.0303526924. The cubic root of 820891 is about 93.6329050671.

It can be divided in two parts, 820 and 891, that added together give a triangular number (1711 = T₅₈).

The spelling of 820891 in words is "eight hundred twenty thousand, eight hundred ninety-one".