686681209 has 8 divisors (see below), whose sum is σ = 700530560. Its totient is φ = 672915600.

The previous prime is 686681189. The next prime is 686681213. The reversal of 686681209 is 902186686.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 686681209 - 2⁷ = 686681081 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (686681249) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4239 + ... + 37300.

It is an arithmetic number, because the mean of its divisors is an integer number (87566320).

Almost surely, 2^686681209 is an apocalyptic number.

It is an amenable number.

686681209 is a deficient number, since it is larger than the sum of its proper divisors (13849351).

686681209 is a wasteful number, since it uses less digits than its factorization.

686681209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41871.

The product of its (nonzero) digits is 248832, while the sum is 46.

The square root of 686681209 is about 26204.6028208786. The cubic root of 686681209 is about 882.2365667711.

The spelling of 686681209 in words is "six hundred eighty-six million, six hundred eighty-one thousand, two hundred nine".