2004021 has 14 divisors (see below), whose sum is σ = 3005750. Its totient is φ = 1335528.

The previous prime is 2004017. The next prime is 2004029. The reversal of 2004021 is 1204002.

It can be written as a sum of positive squares in only one way, i.e., 1347921 + 656100 = 1161^2 + 810^2 .

It is not a de Polignac number, because 2004021 - 2² = 2004017 is a prime.

It is a super-2 number, since 2×2004021² = 8032200336882, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2003994 and 2004012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2004029) 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 13 ways as a sum of consecutive naturals, for example, 646 + ... + 2103.

2^2004021 is an apocalyptic number.

It is an amenable number.

2004021 is a deficient number, since it is larger than the sum of its proper divisors (1001729).

2004021 is an frugal number, since it uses more digits than its factorization.

2004021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2767 (or 2752 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 9.

The square root of 2004021 is about 1415.6344867232. The cubic root of 2004021 is about 126.0764841756.

Adding to 2004021 its reverse (1204002), we get a palindrome (3208023).

The spelling of 2004021 in words is "two million, four thousand, twenty-one".