1840821 has 4 divisors (see below), whose sum is σ = 2454432. Its totient is φ = 1227212.

The previous prime is 1840789. The next prime is 1840829. The reversal of 1840821 is 1280481.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1840821 - 2⁵ = 1840789 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 1840791 and 1840800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1840829) 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, 306801 + ... + 306806.

It is an arithmetic number, because the mean of its divisors is an integer number (613608).

2^1840821 is an apocalyptic number.

It is an amenable number.

1840821 is a deficient number, since it is larger than the sum of its proper divisors (613611).

1840821 is an equidigital number, since it uses as much as digits as its factorization.

1840821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 613610.

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 1840821 is about 1356.7685874901. The cubic root of 1840821 is about 122.5567361785.

The spelling of 1840821 in words is "one million, eight hundred forty thousand, eight hundred twenty-one".