861191 has 2 divisors, whose sum is σ = 861192. Its totient is φ = 861190.

The previous prime is 861167. The next prime is 861199. The reversal of 861191 is 191168.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-861191 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 861191.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (861199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 430595 + 430596.

It is an arithmetic number, because the mean of its divisors is an integer number (430596).

2⁸⁶¹¹⁹¹ is an apocalyptic number.

861191 is a deficient number, since it is larger than the sum of its proper divisors (1).

861191 is an equidigital number, since it uses as much as digits as its factorization.

861191 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 861191 is about 928.0037715441. The cubic root of 861191 is about 95.1407332427.

It can be divided in two parts, 861 and 191, that multiplied together give a triangular number (164451 = T₅₇₃).

The spelling of 861191 in words is "eight hundred sixty-one thousand, one hundred ninety-one".