820009 has 8 divisors (see below), whose sum is σ = 852480. Its totient is φ = 788256.

The previous prime is 819991. The next prime is 820037. The reversal of 820009 is 900028.

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

It is a cyclic number.

It is not a de Polignac number, because 820009 - 2⁵ = 819977 is a prime.

It is a Duffinian number.

820009 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (820109) 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, 3312 + ... + 3550.

It is an arithmetic number, because the mean of its divisors is an integer number (106560).

2⁸²⁰⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

820009 is a deficient number, since it is larger than the sum of its proper divisors (32471).

820009 is a wasteful number, since it uses less digits than its factorization.

820009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 820009 is about 905.5434832188. The cubic root of 820009 is about 93.5993586656.

Adding to 820009 its sum of digits (19), we get a palindrome (820028).

The spelling of 820009 in words is "eight hundred twenty thousand, nine".