866509307217 has 12 divisors (see below), whose sum is σ = 1252589586820. Its totient is φ = 577227472128.

The previous prime is 866509307179. The next prime is 866509307221. The reversal of 866509307217 is 712703905668.

866509307217 is a `hidden beast` number, since 8 + 66 + 509 + 3 + 0 + 72 + 1 + 7 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 698897672001 + 167611635216 = 836001^2 + 409404^2 .

It is not a de Polignac number, because 866509307217 - 2⁷ = 866509307089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (866509307117) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37104292 + ... + 37127637.

Almost surely, 2^866509307217 is an apocalyptic number.

It is an amenable number.

866509307217 is a deficient number, since it is larger than the sum of its proper divisors (386080279603).

866509307217 is a wasteful number, since it uses less digits than its factorization.

866509307217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74233232 (or 74233229 counting only the distinct ones).

The product of its (nonzero) digits is 3810240, while the sum is 54.

The spelling of 866509307217 in words is "eight hundred sixty-six billion, five hundred nine million, three hundred seven thousand, two hundred seventeen".