1605985 has 8 divisors (see below), whose sum is σ = 1979496. Its totient is φ = 1249920.

The previous prime is 1605979. The next prime is 1606009. The reversal of 1605985 is 5895061.

It can be written as a sum of positive squares in 4 ways, for example, as 707281 + 898704 = 841^2 + 948^2 .

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

It is not a de Polignac number, because 1605985 - 2¹³ = 1597793 is a prime.

It is a Duffinian number.

1605985 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1605985.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 4156 + ... + 4525.

It is an arithmetic number, because the mean of its divisors is an integer number (247437).

2^1605985 is an apocalyptic number.

It is an amenable number.

1605985 is a deficient number, since it is larger than the sum of its proper divisors (373511).

1605985 is an equidigital number, since it uses as much as digits as its factorization.

1605985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8723.

The product of its (nonzero) digits is 10800, while the sum is 34.

The square root of 1605985 is about 1267.2746347971. The cubic root of 1605985 is about 117.1063634517.

The spelling of 1605985 in words is "one million, six hundred five thousand, nine hundred eighty-five".