404221021 has 4 divisors (see below), whose sum is σ = 421795872. Its totient is φ = 386646172.

The previous prime is 404221007. The next prime is 404221043. The reversal of 404221021 is 120122404.

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 404221021 - 2⁵ = 404220989 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 404220986 and 404221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (404221421) 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, 8787391 + ... + 8787436.

It is an arithmetic number, because the mean of its divisors is an integer number (105448968).

Almost surely, 2^404221021 is an apocalyptic number.

It is an amenable number.

404221021 is a deficient number, since it is larger than the sum of its proper divisors (17574851).

404221021 is a wasteful number, since it uses less digits than its factorization.

404221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17574850.

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 404221021 is about 20105.2485933400. The cubic root of 404221021 is about 739.3889654015.

Adding to 404221021 its reverse (120122404), we get a palindrome (524343425).

The spelling of 404221021 in words is "four hundred four million, two hundred twenty-one thousand, twenty-one".