820209 has 8 divisors (see below), whose sum is σ = 1177792. Its totient is φ = 504720.

The previous prime is 820201. The next prime is 820213. The reversal of 820209 is 902028.

820209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 820209 - 2³ = 820201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (820201) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10477 + ... + 10554.

It is an arithmetic number, because the mean of its divisors is an integer number (147224).

2⁸²⁰²⁰⁹ is an apocalyptic number.

It is an amenable number.

820209 is a deficient number, since it is larger than the sum of its proper divisors (357583).

820209 is a wasteful number, since it uses less digits than its factorization.

820209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21047.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 820209 is about 905.6539074061. The cubic root of 820209 is about 93.6069676674.

The spelling of 820209 in words is "eight hundred twenty thousand, two hundred nine".