811691 has 2 divisors, whose sum is σ = 811692. Its totient is φ = 811690.

The previous prime is 811667. The next prime is 811697. The reversal of 811691 is 196118.

811691 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 811691 - 2⁶ = 811627 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 811691.

It is not a weakly prime, because it can be changed into another prime (811697) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405845 + 405846.

It is an arithmetic number, because the mean of its divisors is an integer number (405846).

2⁸¹¹⁶⁹¹ is an apocalyptic number.

811691 is a deficient number, since it is larger than the sum of its proper divisors (1).

811691 is an equidigital number, since it uses as much as digits as its factorization.

811691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 432, while the sum is 26.

The square root of 811691 is about 900.9389546468. The cubic root of 811691 is about 93.2817983637.

It can be divided in two parts, 8 and 11691, that multiplied together give a triangular number (93528 = T₄₃₂).

The spelling of 811691 in words is "eight hundred eleven thousand, six hundred ninety-one".