636539868 has 18 divisors (see below), whose sum is σ = 1609031424. Its totient is φ = 212179944.

The previous prime is 636539861. The next prime is 636539963. The reversal of 636539868 is 868935636.

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (636539861) 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 5 ways as a sum of consecutive naturals, for example, 8840796 + ... + 8840867.

Almost surely, 2^636539868 is an apocalyptic number.

It is an amenable number.

636539868 is an abundant number, since it is smaller than the sum of its proper divisors (972491556).

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

636539868 is a wasteful number, since it uses less digits than its factorization.

636539868 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17681673 (or 17681668 counting only the distinct ones).

The product of its digits is 5598720, while the sum is 54.

The square root of 636539868 is about 25229.7417347067. The cubic root of 636539868 is about 860.2180211618.

The spelling of 636539868 in words is "six hundred thirty-six million, five hundred thirty-nine thousand, eight hundred sixty-eight".