138856121 has 2 divisors, whose sum is σ = 138856122. Its totient is φ = 138856120.

The previous prime is 138856103. The next prime is 138856171. The reversal of 138856121 is 121658831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138415225 + 440896 = 11765^2 + 664^2 .

It is a cyclic number.

It is not a de Polignac number, because 138856121 - 2⁶ = 138856057 is a prime.

It is not a weakly prime, because it can be changed into another prime (138856171) 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, 69428060 + 69428061.

It is an arithmetic number, because the mean of its divisors is an integer number (69428061).

Almost surely, 2^138856121 is an apocalyptic number.

It is an amenable number.

138856121 is a deficient number, since it is larger than the sum of its proper divisors (1).

138856121 is an equidigital number, since it uses as much as digits as its factorization.

138856121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11520, while the sum is 35.

The square root of 138856121 is about 11783.7227139814. The cubic root of 138856121 is about 517.8313541425.

The spelling of 138856121 in words is "one hundred thirty-eight million, eight hundred fifty-six thousand, one hundred twenty-one".