6438709138 has 4 divisors (see below), whose sum is σ = 9658063710. Its totient is φ = 3219354568.

The previous prime is 6438709097. The next prime is 6438709159. The reversal of 6438709138 is 8319078346.

It is a happy number.

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

It can be written as a sum of positive squares in only one way, i.e., 6425144649 + 13564489 = 80157^2 + 3683^2 .

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 6438709091 and 6438709100.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1609677283 + ... + 1609677286.

Almost surely, 2^6438709138 is an apocalyptic number.

6438709138 is a deficient number, since it is larger than the sum of its proper divisors (3219354572).

6438709138 is a wasteful number, since it uses less digits than its factorization.

6438709138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3219354571.

The product of its (nonzero) digits is 870912, while the sum is 49.

The square root of 6438709138 is about 80241.5673949606. The cubic root of 6438709138 is about 1860.3711767430.

The spelling of 6438709138 in words is "six billion, four hundred thirty-eight million, seven hundred nine thousand, one hundred thirty-eight".