404021 has 2 divisors, whose sum is σ = 404022. Its totient is φ = 404020.

The previous prime is 404017. The next prime is 404029. The reversal of 404021 is 120404.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 255025 + 148996 = 505^2 + 386^2 .

It is a cyclic number.

It is not a de Polignac number, because 404021 - 2² = 404017 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 403993 and 404011.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (404029) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 202010 + 202011.

It is an arithmetic number, because the mean of its divisors is an integer number (202011).

2⁴⁰⁴⁰²¹ is an apocalyptic number.

It is an amenable number.

404021 is a deficient number, since it is larger than the sum of its proper divisors (1).

404021 is an equidigital number, since it uses as much as digits as its factorization.

404021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 404021 is about 635.6264626335. The cubic root of 404021 is about 73.9266987809.

Adding to 404021 its reverse (120404), we get a palindrome (524425).

The spelling of 404021 in words is "four hundred four thousand, twenty-one", and thus it is an iban number.