865712891 has 2 divisors, whose sum is σ = 865712892. Its totient is φ = 865712890.

The previous prime is 865712873. The next prime is 865712951. The reversal of 865712891 is 198217568.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-865712891 is a prime.

It is not a weakly prime, because it can be changed into another prime (865712821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 432856445 + 432856446.

It is an arithmetic number, because the mean of its divisors is an integer number (432856446).

Almost surely, 2^865712891 is an apocalyptic number.

865712891 is a deficient number, since it is larger than the sum of its proper divisors (1).

865712891 is an equidigital number, since it uses as much as digits as its factorization.

865712891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 241920, while the sum is 47.

The square root of 865712891 is about 29422.9993542467. Note that the first 3 decimals coincide. The cubic root of 865712891 is about 953.0696242607.

The spelling of 865712891 in words is "eight hundred sixty-five million, seven hundred twelve thousand, eight hundred ninety-one".