840009 has 8 divisors (see below), whose sum is σ = 1179040. Its totient is φ = 530496.

The previous prime is 839999. The next prime is 840023. The reversal of 840009 is 900048.

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

It is not a de Polignac number, because 840009 - 2⁹ = 839497 is a prime.

It is a Duffinian number.

840009 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (840109) 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, 7312 + ... + 7425.

It is an arithmetic number, because the mean of its divisors is an integer number (147380).

2⁸⁴⁰⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

840009 is a deficient number, since it is larger than the sum of its proper divisors (339031).

840009 is a wasteful number, since it uses less digits than its factorization.

840009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14759.

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

The square root of 840009 is about 916.5200488805. The cubic root of 840009 is about 94.3542165833.

The spelling of 840009 in words is "eight hundred forty thousand, nine".