138818760721 has 2 divisors, whose sum is σ = 138818760722. Its totient is φ = 138818760720.

The previous prime is 138818760713. The next prime is 138818760733. The reversal of 138818760721 is 127067818831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 135800357121 + 3018403600 = 368511^2 + 54940^2 .

It is an emirp because it is prime and its reverse (127067818831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138818760721 - 2³ = 138818760713 is a prime.

It is a super-2 number, since 2×138818760721² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (138818760761) 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, 69409380360 + 69409380361.

It is an arithmetic number, because the mean of its divisors is an integer number (69409380361).

Almost surely, 2^138818760721 is an apocalyptic number.

It is an amenable number.

138818760721 is a deficient number, since it is larger than the sum of its proper divisors (1).

138818760721 is an equidigital number, since it uses as much as digits as its factorization.

138818760721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 903168, while the sum is 52.

The spelling of 138818760721 in words is "one hundred thirty-eight billion, eight hundred eighteen million, seven hundred sixty thousand, seven hundred twenty-one".