866788526377861 has 4 divisors (see below), whose sum is σ = 866788771963212. Its totient is φ = 866788280792512.

The previous prime is 866788526377853. The next prime is 866788526377877. The reversal of 866788526377861 is 168773625887668.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 540581797672225 + 326206728705636 = 23250415^2 + 18061194^2 .

It is a cyclic number.

It is not a de Polignac number, because 866788526377861 - 2³ = 866788526377853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (866788526377841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 117420100 + ... + 124583533.

It is an arithmetic number, because the mean of its divisors is an integer number (216697192990803).

Almost surely, 2^{866788526377861} is an apocalyptic number.

It is an amenable number.

866788526377861 is a deficient number, since it is larger than the sum of its proper divisors (245585351).

866788526377861 is a wasteful number, since it uses less digits than its factorization.

866788526377861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 245585350.

The product of its digits is 54623600640, while the sum is 88.

The spelling of 866788526377861 in words is "eight hundred sixty-six trillion, seven hundred eighty-eight billion, five hundred twenty-six million, three hundred seventy-seven thousand, eight hundred sixty-one".