870809 has 2 divisors, whose sum is σ = 870810. Its totient is φ = 870808.

The previous prime is 870787. The next prime is 870811. The reversal of 870809 is 908078.

870809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 648025 + 222784 = 805^2 + 472^2 .

It is a cyclic number.

It is not a de Polignac number, because 870809 - 2¹² = 866713 is a prime.

Together with 870811, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (870889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 435404 + 435405.

It is an arithmetic number, because the mean of its divisors is an integer number (435405).

2⁸⁷⁰⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

870809 is a deficient number, since it is larger than the sum of its proper divisors (1).

870809 is an equidigital number, since it uses as much as digits as its factorization.

870809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 870809 is about 933.1714740604. The cubic root of 870809 is about 95.4936081173.

The spelling of 870809 in words is "eight hundred seventy thousand, eight hundred nine".