138169810921 has 2 divisors, whose sum is σ = 138169810922. Its totient is φ = 138169810920.

The previous prime is 138169810819. The next prime is 138169810969. The reversal of 138169810921 is 129018961831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 133926721600 + 4243089321 = 365960^2 + 65139^2 .

It is a cyclic number.

It is not a de Polignac number, because 138169810921 - 2¹¹ = 138169808873 is a prime.

It is not a weakly prime, because it can be changed into another prime (138169810981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69084905460 + 69084905461.

It is an arithmetic number, because the mean of its divisors is an integer number (69084905461).

Almost surely, 2^138169810921 is an apocalyptic number.

It is an amenable number.

138169810921 is a deficient number, since it is larger than the sum of its proper divisors (1).

138169810921 is an equidigital number, since it uses as much as digits as its factorization.

138169810921 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 186624, while the sum is 49.

The spelling of 138169810921 in words is "one hundred thirty-eight billion, one hundred sixty-nine million, eight hundred ten thousand, nine hundred twenty-one".