815985 has 12 divisors (see below), whose sum is σ = 1414452. Its totient is φ = 435168.

The previous prime is 815977. The next prime is 815989. The reversal of 815985 is 589518.

It can be written as a sum of positive squares in 2 ways, for example, as 314721 + 501264 = 561^2 + 708^2 .

It is not a de Polignac number, because 815985 - 2³ = 815977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (815989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9022 + ... + 9111.

It is an arithmetic number, because the mean of its divisors is an integer number (117871).

2⁸¹⁵⁹⁸⁵ is an apocalyptic number.

It is an amenable number.

815985 is a deficient number, since it is larger than the sum of its proper divisors (598467).

815985 is a wasteful number, since it uses less digits than its factorization.

815985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18144 (or 18141 counting only the distinct ones).

The product of its digits is 14400, while the sum is 36.

The square root of 815985 is about 903.3188805732. The cubic root of 815985 is about 93.4460019743.

The spelling of 815985 in words is "eight hundred fifteen thousand, nine hundred eighty-five".