866181545846561 has 16 divisors (see below), whose sum is σ = 1048189355418240. Its totient is φ = 698743708174080.

The previous prime is 866181545846443. The next prime is 866181545846627. The reversal of 866181545846561 is 165648545181668.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 866181545846561 - 2²⁶ = 866181478737697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (866181545846861) 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, 124718006 + ... + 131479823.

It is an arithmetic number, because the mean of its divisors is an integer number (65511834713640).

Almost surely, 2^{866181545846561} is an apocalyptic number.

It is an amenable number.

866181545846561 is a deficient number, since it is larger than the sum of its proper divisors (182007809571679).

866181545846561 is a wasteful number, since it uses less digits than its factorization.

866181545846561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256226264.

The product of its digits is 1327104000, while the sum is 74.

The spelling of 866181545846561 in words is "eight hundred sixty-six trillion, one hundred eighty-one billion, five hundred forty-five million, eight hundred forty-six thousand, five hundred sixty-one".