138440689 has 2 divisors, whose sum is σ = 138440690. Its totient is φ = 138440688.

The previous prime is 138440681. The next prime is 138440719. The reversal of 138440689 is 986044831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 137827600 + 613089 = 11740^2 + 783^2 .

It is an emirp because it is prime and its reverse (986044831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138440689 - 2³ = 138440681 is a prime.

It is not a weakly prime, because it can be changed into another prime (138440681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69220344 + 69220345.

It is an arithmetic number, because the mean of its divisors is an integer number (69220345).

Almost surely, 2^138440689 is an apocalyptic number.

It is an amenable number.

138440689 is a deficient number, since it is larger than the sum of its proper divisors (1).

138440689 is an equidigital number, since it uses as much as digits as its factorization.

138440689 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 165888, while the sum is 43.

The square root of 138440689 is about 11766.0821431775. The cubic root of 138440689 is about 517.3144195205.

It can be divided in two parts, 138440 and 689, that added together give a square (139129 = 373²).

The spelling of 138440689 in words is "one hundred thirty-eight million, four hundred forty thousand, six hundred eighty-nine".