638345138 has 8 divisors (see below), whose sum is σ = 1013842332. Its totient is φ = 300397696.

The previous prime is 638345137. The next prime is 638345143. The reversal of 638345138 is 831543836.

638345138 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 625650169 + 12694969 = 25013^2 + 3563^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 638345095 and 638345104.

It is not an unprimeable number, because it can be changed into a prime (638345137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9387395 + ... + 9387462.

Almost surely, 2^638345138 is an apocalyptic number.

638345138 is a deficient number, since it is larger than the sum of its proper divisors (375497194).

638345138 is a wasteful number, since it uses less digits than its factorization.

638345138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18774876.

The product of its digits is 207360, while the sum is 41.

The square root of 638345138 is about 25265.4930290307. The cubic root of 638345138 is about 861.0304657058.

The spelling of 638345138 in words is "six hundred thirty-eight million, three hundred forty-five thousand, one hundred thirty-eight".