138128321 has 2 divisors, whose sum is σ = 138128322. Its totient is φ = 138128320.

The previous prime is 138128311. The next prime is 138128359. The reversal of 138128321 is 123821831.

138128321 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., 134560000 + 3568321 = 11600^2 + 1889^2 .

It is a cyclic number.

It is not a de Polignac number, because 138128321 - 2¹⁴ = 138111937 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138128311) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69064160 + 69064161.

It is an arithmetic number, because the mean of its divisors is an integer number (69064161).

Almost surely, 2^138128321 is an apocalyptic number.

It is an amenable number.

138128321 is a deficient number, since it is larger than the sum of its proper divisors (1).

138128321 is an equidigital number, since it uses as much as digits as its factorization.

138128321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2304, while the sum is 29.

The square root of 138128321 is about 11752.8005598666. The cubic root of 138128321 is about 516.9250490261.

The spelling of 138128321 in words is "one hundred thirty-eight million, one hundred twenty-eight thousand, three hundred twenty-one".