636224221 has 4 divisors (see below), whose sum is σ = 636577344. Its totient is φ = 635871100.

The previous prime is 636224219. The next prime is 636224233. The reversal of 636224221 is 122422636.

636224221 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 636224221 - 2¹ = 636224219 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 636224221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636224021) 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, 173845 + ... + 177466.

It is an arithmetic number, because the mean of its divisors is an integer number (159144336).

Almost surely, 2^636224221 is an apocalyptic number.

It is an amenable number.

636224221 is a deficient number, since it is larger than the sum of its proper divisors (353123).

636224221 is a wasteful number, since it uses less digits than its factorization.

636224221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 353122.

The product of its digits is 6912, while the sum is 28.

The square root of 636224221 is about 25223.4855045848. The cubic root of 636224221 is about 860.0758095241.

Adding to 636224221 its reverse (122422636), we get a palindrome (758646857).

The spelling of 636224221 in words is "six hundred thirty-six million, two hundred twenty-four thousand, two hundred twenty-one".