138078121 has 2 divisors, whose sum is σ = 138078122. Its totient is φ = 138078120.

The previous prime is 138078103. The next prime is 138078137. The reversal of 138078121 is 121870831.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 92852496 + 45225625 = 9636^2 + 6725^2 .

It is an emirp because it is prime and its reverse (121870831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138078121 - 2⁹ = 138077609 is a prime.

It is not a weakly prime, because it can be changed into another prime (138075121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69039060 + 69039061.

It is an arithmetic number, because the mean of its divisors is an integer number (69039061).

Almost surely, 2^138078121 is an apocalyptic number.

It is an amenable number.

138078121 is a deficient number, since it is larger than the sum of its proper divisors (1).

138078121 is an equidigital number, since it uses as much as digits as its factorization.

138078121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2688, while the sum is 31.

The square root of 138078121 is about 11750.6647046029. The cubic root of 138078121 is about 516.8624193845.

The spelling of 138078121 in words is "one hundred thirty-eight million, seventy-eight thousand, one hundred twenty-one".