865266191 has 2 divisors, whose sum is σ = 865266192. Its totient is φ = 865266190.

The previous prime is 865266169. The next prime is 865266197. The reversal of 865266191 is 191662568.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-865266191 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (865266197) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432633095 + 432633096.

It is an arithmetic number, because the mean of its divisors is an integer number (432633096).

Almost surely, 2^865266191 is an apocalyptic number.

865266191 is a deficient number, since it is larger than the sum of its proper divisors (1).

865266191 is an equidigital number, since it uses as much as digits as its factorization.

865266191 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 44.

The square root of 865266191 is about 29415.4073743676. The cubic root of 865266191 is about 952.9056709640.

The spelling of 865266191 in words is "eight hundred sixty-five million, two hundred sixty-six thousand, one hundred ninety-one".