866181545846861 has 2 divisors, whose sum is σ = 866181545846862. Its totient is φ = 866181545846860.

The previous prime is 866181545846843. The next prime is 866181545846957. The reversal of 866181545846861 is 168648545181668.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 766227740510761 + 99953805336100 = 27680819^2 + 9997690^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-866181545846861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (866181545846831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433090772923430 + 433090772923431.

It is an arithmetic number, because the mean of its divisors is an integer number (433090772923431).

Almost surely, 2^{866181545846861} is an apocalyptic number.

It is an amenable number.

866181545846861 is a deficient number, since it is larger than the sum of its proper divisors (1).

866181545846861 is an equidigital number, since it uses as much as digits as its factorization.

866181545846861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2123366400, while the sum is 77.

The spelling of 866181545846861 in words is "eight hundred sixty-six trillion, one hundred eighty-one billion, five hundred forty-five million, eight hundred forty-six thousand, eight hundred sixty-one".