6438635818 has 16 divisors (see below), whose sum is σ = 9924763464. Its totient is φ = 3130877440.

The previous prime is 6438635813. The next prime is 6438635873. The reversal of 6438635818 is 8185368346.

It can be written as a sum of positive squares in 4 ways, for example, as 4155994089 + 2282641729 = 64467^2 + 47777^2 .

It is not an unprimeable number, because it can be changed into a prime (6438635813) 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 7 ways as a sum of consecutive naturals, for example, 97855 + ... + 149842.

Almost surely, 2^6438635818 is an apocalyptic number.

6438635818 is a deficient number, since it is larger than the sum of its proper divisors (3486127646).

6438635818 is a wasteful number, since it uses less digits than its factorization.

6438635818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248057.

The product of its digits is 3317760, while the sum is 52.

The square root of 6438635818 is about 80241.1105232224. The cubic root of 6438635818 is about 1860.3641151343.

The spelling of 6438635818 in words is "six billion, four hundred thirty-eight million, six hundred thirty-five thousand, eight hundred eighteen".