686712820217 has 4 divisors (see below), whose sum is σ = 688306121856. Its totient is φ = 685119518580.

The previous prime is 686712820193. The next prime is 686712820273. The reversal of 686712820217 is 712028217686.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 686712820217 - 2⁶ = 686712820153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686712820517) 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, 796650173 + ... + 796651034.

It is an arithmetic number, because the mean of its divisors is an integer number (172076530464).

Almost surely, 2^686712820217 is an apocalyptic number.

It is an amenable number.

686712820217 is a deficient number, since it is larger than the sum of its proper divisors (1593301639).

686712820217 is a wasteful number, since it uses less digits than its factorization.

686712820217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1593301638.

The product of its (nonzero) digits is 903168, while the sum is 50.

The spelling of 686712820217 in words is "six hundred eighty-six billion, seven hundred twelve million, eight hundred twenty thousand, two hundred seventeen".