636403218 has 64 divisors (see below), whose sum is σ = 1426747392. Its totient is φ = 187591680.

The previous prime is 636403217. The next prime is 636403237. The reversal of 636403218 is 812304636.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (636403213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 598155 + ... + 599217.

It is an arithmetic number, because the mean of its divisors is an integer number (22292928).

Almost surely, 2^636403218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 636403218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (713373696).

636403218 is an abundant number, since it is smaller than the sum of its proper divisors (790344174).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

636403218 is a wasteful number, since it uses less digits than its factorization.

636403218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1319.

The product of its (nonzero) digits is 20736, while the sum is 33.

The square root of 636403218 is about 25227.0334760154. The cubic root of 636403218 is about 860.1564606264.

The spelling of 636403218 in words is "six hundred thirty-six million, four hundred three thousand, two hundred eighteen".