20404221 has 4 divisors (see below), whose sum is σ = 27205632. Its totient is φ = 13602812.

The previous prime is 20404213. The next prime is 20404249. The reversal of 20404221 is 12240402.

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 20404221 - 2³ = 20404213 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20404221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20404261) 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, 3400701 + ... + 3400706.

It is an arithmetic number, because the mean of its divisors is an integer number (6801408).

Almost surely, 2^20404221 is an apocalyptic number.

It is an amenable number.

20404221 is a deficient number, since it is larger than the sum of its proper divisors (6801411).

20404221 is an equidigital number, since it uses as much as digits as its factorization.

20404221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6801410.

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 20404221 is about 4517.1031646399. The cubic root of 20404221 is about 273.2582857948.

Adding to 20404221 its reverse (12240402), we get a palindrome (32644623).

The spelling of 20404221 in words is "twenty million, four hundred four thousand, two hundred twenty-one".