685109 has 2 divisors, whose sum is σ = 685110. Its totient is φ = 685108.

The previous prime is 685103. The next prime is 685123. The reversal of 685109 is 901586.

685109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 624100 + 61009 = 790^2 + 247^2 .

It is a cyclic number.

It is not a de Polignac number, because 685109 - 2⁴ = 685093 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a zygodrome in base 7.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (685103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342554 + 342555.

It is an arithmetic number, because the mean of its divisors is an integer number (342555).

2⁶⁸⁵¹⁰⁹ is an apocalyptic number.

It is an amenable number.

685109 is a deficient number, since it is larger than the sum of its proper divisors (1).

685109 is an equidigital number, since it uses as much as digits as its factorization.

685109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 685109 is about 827.7131145512. The cubic root of 685109 is about 88.1562736278.

The spelling of 685109 in words is "six hundred eighty-five thousand, one hundred nine".