636026221 has 4 divisors (see below), whose sum is σ = 636149052. Its totient is φ = 635903392.

The previous prime is 636026213. The next prime is 636026257. The reversal of 636026221 is 122620636.

It is a happy number.

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 294294025 + 341732196 = 17155^2 + 18486^2 .

It is a cyclic number.

It is not a de Polignac number, because 636026221 - 2³ = 636026213 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 636026221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636026621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53290 + ... + 64123.

It is an arithmetic number, because the mean of its divisors is an integer number (159037263).

Almost surely, 2^636026221 is an apocalyptic number.

It is an amenable number.

636026221 is a deficient number, since it is larger than the sum of its proper divisors (122831).

636026221 is a wasteful number, since it uses less digits than its factorization.

636026221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 122830.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 636026221 is about 25219.5602856196. The cubic root of 636026221 is about 859.9865785719.

Adding to 636026221 its reverse (122620636), we get a palindrome (758646857).

The spelling of 636026221 in words is "six hundred thirty-six million, twenty-six thousand, two hundred twenty-one".