404420021 has 4 divisors (see below), whose sum is σ = 428209452. Its totient is φ = 380630592.

The previous prime is 404420011. The next prime is 404420069. The reversal of 404420021 is 120024404.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 316341796 + 88078225 = 17786^2 + 9385^2 .

It is a cyclic number.

It is not a de Polignac number, because 404420021 - 2⁶ = 404419957 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17), and also a Moran number because the ratio is a prime number: 23789413 = 404420021 / (4 + 0 + 4 + 4 + 2 + 0 + 0 + 2 + 1).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (404420011) 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, 11894690 + ... + 11894723.

It is an arithmetic number, because the mean of its divisors is an integer number (107052363).

Almost surely, 2^404420021 is an apocalyptic number.

It is an amenable number.

404420021 is a deficient number, since it is larger than the sum of its proper divisors (23789431).

404420021 is a wasteful number, since it uses less digits than its factorization.

404420021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23789430.

The product of its (nonzero) digits is 256, while the sum is 17.

The square root of 404420021 is about 20110.1969408557. The cubic root of 404420021 is about 739.5102804391.

Adding to 404420021 its reverse (120024404), we get a palindrome (524444425).

The spelling of 404420021 in words is "four hundred four million, four hundred twenty thousand, twenty-one".