1804821 has 4 divisors (see below), whose sum is σ = 2406432. Its totient is φ = 1203212.

The previous prime is 1804819. The next prime is 1804841. The reversal of 1804821 is 1284081.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1284081 = 3 ⋅428027.

It is a cyclic number.

It is not a de Polignac number, because 1804821 - 2¹ = 1804819 is a prime.

It is a D-number.

It is a junction number, because it is equal to n+sod(n) for n = 1804791 and 1804800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1804801) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 300801 + ... + 300806.

It is an arithmetic number, because the mean of its divisors is an integer number (601608).

2^1804821 is an apocalyptic number.

It is an amenable number.

1804821 is a deficient number, since it is larger than the sum of its proper divisors (601611).

1804821 is an equidigital number, since it uses as much as digits as its factorization.

1804821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 601610.

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

The square root of 1804821 is about 1343.4362657008. The cubic root of 1804821 is about 121.7525441945.

The spelling of 1804821 in words is "one million, eight hundred four thousand, eight hundred twenty-one".