866761278035561 has 16 divisors (see below), whose sum is σ = 870127201843200. Its totient is φ = 863400820626240.

The previous prime is 866761278035461. The next prime is 866761278035599. The reversal of 866761278035561 is 165530872167668.

It is a cyclic number.

It is not a de Polignac number, because 866761278035561 - 2²⁶ = 866761210926697 is a prime.

It is a super-2 number, since 2×866761278035561² (a number of 31 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (866761278035461) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1431246056 + ... + 1431851526.

It is an arithmetic number, because the mean of its divisors is an integer number (54382950115200).

Almost surely, 2^{866761278035561} is an apocalyptic number.

It is an amenable number.

866761278035561 is a deficient number, since it is larger than the sum of its proper divisors (3365923807639).

866761278035561 is a wasteful number, since it uses less digits than its factorization.

866761278035561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 609976.

The product of its (nonzero) digits is 609638400, while the sum is 71.

The spelling of 866761278035561 in words is "eight hundred sixty-six trillion, seven hundred sixty-one billion, two hundred seventy-eight million, thirty-five thousand, five hundred sixty-one".