865857191 has 2 divisors, whose sum is σ = 865857192. Its totient is φ = 865857190.

The previous prime is 865857169. The next prime is 865857193. The reversal of 865857191 is 191758568.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 865857191 - 2⁶ = 865857127 is a prime.

Together with 865857193, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (865857193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432928595 + 432928596.

It is an arithmetic number, because the mean of its divisors is an integer number (432928596).

Almost surely, 2^865857191 is an apocalyptic number.

865857191 is a deficient number, since it is larger than the sum of its proper divisors (1).

865857191 is an equidigital number, since it uses as much as digits as its factorization.

865857191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 604800, while the sum is 50.

The square root of 865857191 is about 29425.4514153989. The cubic root of 865857191 is about 953.1225749590.

The spelling of 865857191 in words is "eight hundred sixty-five million, eight hundred fifty-seven thousand, one hundred ninety-one".