811861 has 2 divisors, whose sum is σ = 811862. Its totient is φ = 811860.

The previous prime is 811819. The next prime is 811871. The reversal of 811861 is 168118.

It is a happy number.

811861 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 can be written as a sum of positive squares in only one way, i.e., 463761 + 348100 = 681^2 + 590^2 .

It is a cyclic number.

It is not a de Polignac number, because 811861 - 2¹³ = 803669 is a prime.

It is a plaindrome in base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (811871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 405930 + 405931.

It is an arithmetic number, because the mean of its divisors is an integer number (405931).

2⁸¹¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

811861 is a deficient number, since it is larger than the sum of its proper divisors (1).

811861 is an equidigital number, since it uses as much as digits as its factorization.

811861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 384, while the sum is 25.

The square root of 811861 is about 901.0332957222. The cubic root of 811861 is about 93.2883102009.

Adding to 811861 its reverse (168118), we get a palindrome (979979).

The spelling of 811861 in words is "eight hundred eleven thousand, eight hundred sixty-one".