809985 has 16 divisors (see below), whose sum is σ = 1414080. Its totient is φ = 392640.

The previous prime is 809983. The next prime is 809993. The reversal of 809985 is 589908.

It is not a de Polignac number, because 809985 - 2¹ = 809983 is a prime.

It is not an unprimeable number, because it can be changed into a prime (809981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2290 + ... + 2619.

It is an arithmetic number, because the mean of its divisors is an integer number (88380).

It is a Proth number, since it is equal to 791 ⋅ 2¹⁰ + 1 and 791 < 2¹⁰.

2⁸⁰⁹⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

809985 is a deficient number, since it is larger than the sum of its proper divisors (604095).

809985 is a wasteful number, since it uses less digits than its factorization.

809985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4928.

The product of its (nonzero) digits is 25920, while the sum is 39.

The square root of 809985 is about 899.9916666281. The cubic root of 809985 is about 93.2163997616.

It can be divided in two parts, 80998 and 5, that added together give a triangular number (81003 = T₄₀₂).

The spelling of 809985 in words is "eight hundred nine thousand, nine hundred eighty-five".