138197681 has 2 divisors, whose sum is σ = 138197682. Its totient is φ = 138197680.

The previous prime is 138197671. The next prime is 138197699. The reversal of 138197681 is 186791831.

138197681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 133287025 + 4910656 = 11545^2 + 2216^2 .

It is a cyclic number.

It is not a de Polignac number, because 138197681 - 2²⁶ = 71088817 is a prime.

It is a super-2 number, since 2×138197681² = 38197198067555522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138197651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69098840 + 69098841.

It is an arithmetic number, because the mean of its divisors is an integer number (69098841).

Almost surely, 2^138197681 is an apocalyptic number.

It is an amenable number.

138197681 is a deficient number, since it is larger than the sum of its proper divisors (1).

138197681 is an equidigital number, since it uses as much as digits as its factorization.

138197681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 44.

The square root of 138197681 is about 11755.7509755864. The cubic root of 138197681 is about 517.0115577681.

The spelling of 138197681 in words is "one hundred thirty-eight million, one hundred ninety-seven thousand, six hundred eighty-one".