680809 has 2 divisors, whose sum is σ = 680810. Its totient is φ = 680808.

The previous prime is 680803. The next prime is 680831. The reversal of 680809 is 908086.

680809 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., 518400 + 162409 = 720^2 + 403^2 .

It is a cyclic number.

It is not a de Polignac number, because 680809 - 2⁷ = 680681 is a prime.

It is a Chen prime.

680809 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (680803) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340404 + 340405.

It is an arithmetic number, because the mean of its divisors is an integer number (340405).

2⁶⁸⁰⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

680809 is a deficient number, since it is larger than the sum of its proper divisors (1).

680809 is an equidigital number, since it uses as much as digits as its factorization.

680809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 680809 is about 825.1115076158. Note that the first 3 decimals coincide. The cubic root of 680809 is about 87.9714525170.

The spelling of 680809 in words is "six hundred eighty thousand, eight hundred nine".