866786517366881 has 2 divisors, whose sum is σ = 866786517366882. Its totient is φ = 866786517366880.

The previous prime is 866786517366829. The next prime is 866786517366907. The reversal of 866786517366881 is 188663715687668.

866786517366881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 811760386805281 + 55026130561600 = 28491409^2 + 7417960^2 .

It is a cyclic number.

It is not a de Polignac number, because 866786517366881 - 2⁴² = 862388470855777 is a prime.

It is a super-2 number, since 2×866786517366881² (a number of 31 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 866786517366793 and 866786517366802.

It is not a weakly prime, because it can be changed into another prime (866786517366811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 433393258683440 + 433393258683441.

It is an arithmetic number, because the mean of its divisors is an integer number (433393258683441).

Almost surely, 2^{866786517366881} is an apocalyptic number.

It is an amenable number.

866786517366881 is a deficient number, since it is larger than the sum of its proper divisors (1).

866786517366881 is an equidigital number, since it uses as much as digits as its factorization.

866786517366881 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23410114560, while the sum is 86.

The spelling of 866786517366881 in words is "eight hundred sixty-six trillion, seven hundred eighty-six billion, five hundred seventeen million, three hundred sixty-six thousand, eight hundred eighty-one".