404005521 has 4 divisors (see below), whose sum is σ = 538674032. Its totient is φ = 269337012.

The previous prime is 404005519. The next prime is 404005523. The reversal of 404005521 is 125500404.

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 an interprime number because it is at equal distance from previous prime (404005519) and next prime (404005523).

It is not a de Polignac number, because 404005521 - 2¹ = 404005519 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (404005523) 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, 67334251 + ... + 67334256.

It is an arithmetic number, because the mean of its divisors is an integer number (134668508).

Almost surely, 2^404005521 is an apocalyptic number.

It is an amenable number.

404005521 is a deficient number, since it is larger than the sum of its proper divisors (134668511).

404005521 is a wasteful number, since it uses less digits than its factorization.

404005521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134668510.

The product of its (nonzero) digits is 800, while the sum is 21.

The square root of 404005521 is about 20099.8885817807. Note that the first 3 decimals coincide. The cubic root of 404005521 is about 739.2575466662.

Adding to 404005521 its reverse (125500404), we get a palindrome (529505925).

The spelling of 404005521 in words is "four hundred four million, five thousand, five hundred twenty-one".