866786513765985 has 56 divisors (see below), whose sum is σ = 1559508995281320. Its totient is φ = 462284161984512.

The previous prime is 866786513765941. The next prime is 866786513765989. The reversal of 866786513765985 is 589567315687668.

866786513765985 is a `hidden beast` number, since 8 + 6 + 6 + 7 + 8 + 6 + 5 + 1 + 3 + 7 + 6 + 598 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 288265489294689 + 578521024471296 = 16978383^2 + 24052464^2 .

It is not a de Polignac number, because 866786513765985 - 2⁷ = 866786513765857 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 866786513765895 and 866786513765904.

It is not an unprimeable number, because it can be changed into a prime (866786513765989) by changing a digit.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 1323963201 + ... + 1324617729.

Almost surely, 2^{866786513765985} is an apocalyptic number.

It is an amenable number.

866786513765985 is a deficient number, since it is larger than the sum of its proper divisors (692722481515335).

866786513765985 is an equidigital number, since it uses as much as digits as its factorization.

866786513765985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1017869 (or 1017854 counting only the distinct ones).

The product of its digits is 109734912000, while the sum is 90.

The spelling of 866786513765985 in words is "eight hundred sixty-six trillion, seven hundred eighty-six billion, five hundred thirteen million, seven hundred sixty-five thousand, nine hundred eighty-five".