811961 has 2 divisors, whose sum is σ = 811962. Its totient is φ = 811960.

The previous prime is 811957. The next prime is 811981. The reversal of 811961 is 169118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 739600 + 72361 = 860^2 + 269^2 .

It is a cyclic number.

It is not a de Polignac number, because 811961 - 2² = 811957 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 811961.

It is not a weakly prime, because it can be changed into another prime (811931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405980 + 405981.

It is an arithmetic number, because the mean of its divisors is an integer number (405981).

2⁸¹¹⁹⁶¹ is an apocalyptic number.

It is an amenable number.

811961 is a deficient number, since it is larger than the sum of its proper divisors (1).

811961 is an equidigital number, since it uses as much as digits as its factorization.

811961 is an odious number, because the sum of its binary digits is odd.

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

The square root of 811961 is about 901.0887858585. The cubic root of 811961 is about 93.2921402687.

The spelling of 811961 in words is "eight hundred eleven thousand, nine hundred sixty-one".