684809 has 2 divisors, whose sum is σ = 684810. Its totient is φ = 684808.

The previous prime is 684799. The next prime is 684829. The reversal of 684809 is 908486.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 644809 + 40000 = 803^2 + 200^2 .

It is a cyclic number.

It is not a de Polignac number, because 684809 - 2⁴ = 684793 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (684829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 342404 + 342405.

It is an arithmetic number, because the mean of its divisors is an integer number (342405).

2⁶⁸⁴⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

684809 is a deficient number, since it is larger than the sum of its proper divisors (1).

684809 is an equidigital number, since it uses as much as digits as its factorization.

684809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 684809 is about 827.5318724980. The cubic root of 684809 is about 88.1434042677.

The spelling of 684809 in words is "six hundred eighty-four thousand, eight hundred nine".