1681865 has 4 divisors (see below), whose sum is σ = 2018244. Its totient is φ = 1345488.

The previous prime is 1681853. The next prime is 1681871. The reversal of 1681865 is 5681861.

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 1024144 + 657721 = 1012^2 + 811^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1681865 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 168182 + ... + 168191.

It is an arithmetic number, because the mean of its divisors is an integer number (504561).

2^1681865 is an apocalyptic number.

It is an amenable number.

1681865 is a deficient number, since it is larger than the sum of its proper divisors (336379).

1681865 is an equidigital number, since it uses as much as digits as its factorization.

1681865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 336378.

The product of its digits is 11520, while the sum is 35.

The square root of 1681865 is about 1296.8673794957. The cubic root of 1681865 is about 118.9224125272.

The spelling of 1681865 in words is "one million, six hundred eighty-one thousand, eight hundred sixty-five".