866788807221578 has 16 divisors (see below), whose sum is σ = 1305204135195240. Its totient is φ = 431721546622656.

The previous prime is 866788807221529. The next prime is 866788807221581. The reversal of 866788807221578 is 875122708887668.

It can be written as a sum of positive squares in 4 ways, for example, as 373385787715249 + 493403019506329 = 19323193^2 + 22212677^2 .

It is a junction number, because it is equal to n+sod(n) for n = 866788807221496 and 866788807221505.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 193904501 + ... + 198324312.

Almost surely, 2^{866788807221578} is an apocalyptic number.

866788807221578 is a deficient number, since it is larger than the sum of its proper divisors (438415327973662).

866788807221578 is a wasteful number, since it uses less digits than its factorization.

866788807221578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 392233081.

The product of its (nonzero) digits is 8092385280, while the sum is 83.

The spelling of 866788807221578 in words is "eight hundred sixty-six trillion, seven hundred eighty-eight billion, eight hundred seven million, two hundred twenty-one thousand, five hundred seventy-eight".