1845821 has 4 divisors (see below), whose sum is σ = 1909500. Its totient is φ = 1782144.

The previous prime is 1845791. The next prime is 1845827. The reversal of 1845821 is 1285481.

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 657721 + 1188100 = 811^2 + 1090^2 .

It is a cyclic number.

It is not a de Polignac number, because 1845821 - 2⁶ = 1845757 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29), and also a Moran number because the ratio is a prime number: 63649 = 1845821 / (1 + 8 + 4 + 5 + 8 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1845827) 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 3 ways as a sum of consecutive naturals, for example, 31796 + ... + 31853.

It is an arithmetic number, because the mean of its divisors is an integer number (477375).

2^1845821 is an apocalyptic number.

It is an amenable number.

1845821 is a deficient number, since it is larger than the sum of its proper divisors (63679).

1845821 is an equidigital number, since it uses as much as digits as its factorization.

1845821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 63678.

The product of its digits is 2560, while the sum is 29.

The square root of 1845821 is about 1358.6099513841. The cubic root of 1845821 is about 122.6675978912.

The spelling of 1845821 in words is "one million, eight hundred forty-five thousand, eight hundred twenty-one".