1821685 has 4 divisors (see below), whose sum is σ = 2186028. Its totient is φ = 1457344.

The previous prime is 1821679. The next prime is 1821691. The reversal of 1821685 is 5861281.

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

It is an interprime number because it is at equal distance from previous prime (1821679) and next prime (1821691).

It can be written as a sum of positive squares in 2 ways, for example, as 1313316 + 508369 = 1146^2 + 713^2 .

It is a cyclic number.

It is not a de Polignac number, because 1821685 - 2¹¹ = 1819637 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 182164 + ... + 182173.

It is an arithmetic number, because the mean of its divisors is an integer number (546507).

2^1821685 is an apocalyptic number.

It is an amenable number.

1821685 is a deficient number, since it is larger than the sum of its proper divisors (364343).

1821685 is an equidigital number, since it uses as much as digits as its factorization.

1821685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364342.

The product of its digits is 3840, while the sum is 31.

The square root of 1821685 is about 1349.6981143945. The cubic root of 1821685 is about 122.1305822101.

The spelling of 1821685 in words is "one million, eight hundred twenty-one thousand, six hundred eighty-five".