138320427821 has 2 divisors, whose sum is σ = 138320427822. Its totient is φ = 138320427820.

The previous prime is 138320427809. The next prime is 138320427901. The reversal of 138320427821 is 128724023831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 77170062025 + 61150365796 = 277795^2 + 247286^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138320427821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138320427221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69160213910 + 69160213911.

It is an arithmetic number, because the mean of its divisors is an integer number (69160213911).

Almost surely, 2^138320427821 is an apocalyptic number.

It is an amenable number.

138320427821 is a deficient number, since it is larger than the sum of its proper divisors (1).

138320427821 is an equidigital number, since it uses as much as digits as its factorization.

138320427821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 129024, while the sum is 41.

The spelling of 138320427821 in words is "one hundred thirty-eight billion, three hundred twenty million, four hundred twenty-seven thousand, eight hundred twenty-one".