685691 has 8 divisors (see below), whose sum is σ = 729600. Its totient is φ = 642600.

The previous prime is 685679. The next prime is 685697. The reversal of 685691 is 196586.

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 685691 - 2¹⁸ = 423547 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 685691.

It is not an unprimeable number, because it can be changed into a prime (685697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2750 + ... + 2988.

It is an arithmetic number, because the mean of its divisors is an integer number (91200).

2⁶⁸⁵⁶⁹¹ is an apocalyptic number.

685691 is a deficient number, since it is larger than the sum of its proper divisors (43909).

685691 is a wasteful number, since it uses less digits than its factorization.

685691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409.

The product of its digits is 12960, while the sum is 35.

The square root of 685691 is about 828.0646110057. The cubic root of 685691 is about 88.1812294765.

The spelling of 685691 in words is "six hundred eighty-five thousand, six hundred ninety-one".