1686385 has 4 divisors (see below), whose sum is σ = 2023668. Its totient is φ = 1349104.

The previous prime is 1686367. The next prime is 1686389. The reversal of 1686385 is 5836861.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1073296 + 613089 = 1036^2 + 783^2 .

It is a cyclic number.

It is not a de Polignac number, because 1686385 - 2⁵ = 1686353 is a prime.

It is a Duffinian number.

1686385 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1686389) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 168634 + ... + 168643.

It is an arithmetic number, because the mean of its divisors is an integer number (505917).

2^1686385 is an apocalyptic number.

It is an amenable number.

1686385 is a deficient number, since it is larger than the sum of its proper divisors (337283).

1686385 is an equidigital number, since it uses as much as digits as its factorization.

1686385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337282.

The product of its digits is 34560, while the sum is 37.

The square root of 1686385 is about 1298.6088710616. The cubic root of 1686385 is about 119.0288516066.

The spelling of 1686385 in words is "one million, six hundred eighty-six thousand, three hundred eighty-five".