686904467209 has 3 divisors (see below), whose sum is σ = 686905296007. Its totient is φ = 686903638412.

The previous prime is 686904467177. The next prime is 686904467233. The reversal of 686904467209 is 902764409686.

The square root of 686904467209 is 828797.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 2029052025 + 684875415184 = 45045^2 + 827572^2 .

It is not a de Polignac number, because 686904467209 - 2⁵ = 686904467177 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686904467239) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 414399 + ... + 1243195.

Almost surely, 2^686904467209 is an apocalyptic number.

686904467209 is the 828797-th square number.

686904467209 is the 414399-th centered octagonal number.

It is an amenable number.

686904467209 is a deficient number, since it is larger than the sum of its proper divisors (828798).

686904467209 is an frugal number, since it uses more digits than its factorization.

686904467209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1657594 (or 828797 counting only the distinct ones).

The product of its (nonzero) digits is 31352832, while the sum is 61.

The spelling of 686904467209 in words is "six hundred eighty-six billion, nine hundred four million, four hundred sixty-seven thousand, two hundred nine".