404405021 has 4 divisors (see below), whose sum is σ = 421987872. Its totient is φ = 386822172.

The previous prime is 404405009. The next prime is 404405039. The reversal of 404405021 is 120504404.

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 404405021 - 2¹⁴ = 404388637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 404404984 and 404405002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (404405041) 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, 8791391 + ... + 8791436.

It is an arithmetic number, because the mean of its divisors is an integer number (105496968).

Almost surely, 2^404405021 is an apocalyptic number.

It is an amenable number.

404405021 is a deficient number, since it is larger than the sum of its proper divisors (17582851).

404405021 is a wasteful number, since it uses less digits than its factorization.

404405021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17582850.

The product of its (nonzero) digits is 640, while the sum is 20.

The square root of 404405021 is about 20109.8239922681. The cubic root of 404405021 is about 739.5011374765.

Adding to 404405021 its reverse (120504404), we get a palindrome (524909425).

The spelling of 404405021 in words is "four hundred four million, four hundred five thousand, twenty-one".