865166365566 has 12 divisors (see below), whose sum is σ = 1874527125432. Its totient is φ = 288388788516.

The previous prime is 865166365541. The next prime is 865166365571. The reversal of 865166365566 is 665563661568.

It is a happy number.

865166365566 is a `hidden beast` number, since 8 + 6 + 5 + 1 + 6 + 6 + 3 + 65 + 566 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 24032399026 + ... + 24032399061.

It is an arithmetic number, because the mean of its divisors is an integer number (156210593786).

Almost surely, 2^865166365566 is an apocalyptic number.

865166365566 is an abundant number, since it is smaller than the sum of its proper divisors (1009360759866).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

865166365566 is a wasteful number, since it uses less digits than its factorization.

865166365566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48064798095 (or 48064798092 counting only the distinct ones).

The product of its digits is 139968000, while the sum is 63.

The spelling of 865166365566 in words is "eight hundred sixty-five billion, one hundred sixty-six million, three hundred sixty-five thousand, five hundred sixty-six".