636440243 has 4 divisors (see below), whose sum is σ = 638612688. Its totient is φ = 634267800.

The previous prime is 636440227. The next prime is 636440279. The reversal of 636440243 is 342044636.

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

It is a cyclic number.

It is not a de Polignac number, because 636440243 - 2⁴ = 636440227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (636440143) 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, 1085783 + ... + 1086368.

It is an arithmetic number, because the mean of its divisors is an integer number (159653172).

Almost surely, 2^636440243 is an apocalyptic number.

636440243 is a deficient number, since it is larger than the sum of its proper divisors (2172445).

636440243 is a wasteful number, since it uses less digits than its factorization.

636440243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2172444.

The product of its (nonzero) digits is 41472, while the sum is 32.

The square root of 636440243 is about 25227.7673011307. The cubic root of 636440243 is about 860.1731411808.

Adding to 636440243 its reverse (342044636), we get a palindrome (978484879).

The spelling of 636440243 in words is "six hundred thirty-six million, four hundred forty thousand, two hundred forty-three".