138009989 has 4 divisors (see below), whose sum is σ = 148626156. Its totient is φ = 127393824.

The previous prime is 138009979. The next prime is 138009997. The reversal of 138009989 is 989900831.

138009989 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 989900831 = 109 ⋅9081659.

It can be written as a sum of positive squares in 2 ways, for example, as 72965764 + 65044225 = 8542^2 + 8065^2 .

It is a cyclic number.

It is not a de Polignac number, because 138009989 - 2¹⁶ = 137944453 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138009979) 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, 5308064 + ... + 5308089.

It is an arithmetic number, because the mean of its divisors is an integer number (37156539).

Almost surely, 2^138009989 is an apocalyptic number.

It is an amenable number.

138009989 is a deficient number, since it is larger than the sum of its proper divisors (10616167).

138009989 is a wasteful number, since it uses less digits than its factorization.

138009989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10616166.

The product of its (nonzero) digits is 139968, while the sum is 47.

The square root of 138009989 is about 11747.7652768516. The cubic root of 138009989 is about 516.7773934496. Note that the first 3 decimals are identical.

The spelling of 138009989 in words is "one hundred thirty-eight million, nine thousand, nine hundred eighty-nine".