138738728 has 8 divisors (see below), whose sum is σ = 260135130. Its totient is φ = 69369360.

The previous prime is 138738727. The next prime is 138738731. The reversal of 138738728 is 827837831.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 91431844 + 47306884 = 9562^2 + 6878^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (138738727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8671163 + ... + 8671178.

Almost surely, 2^138738728 is an apocalyptic number.

It is an amenable number.

138738728 is a deficient number, since it is larger than the sum of its proper divisors (121396402).

138738728 is a wasteful number, since it uses less digits than its factorization.

138738728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17342347 (or 17342343 counting only the distinct ones).

The product of its digits is 451584, while the sum is 47.

The square root of 138738728 is about 11778.7405099187. The cubic root of 138738728 is about 517.6853831069.

The spelling of 138738728 in words is "one hundred thirty-eight million, seven hundred thirty-eight thousand, seven hundred twenty-eight".