138905281 has 2 divisors, whose sum is σ = 138905282. Its totient is φ = 138905280.

The previous prime is 138905269. The next prime is 138905339. The reversal of 138905281 is 182509831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 112021056 + 26884225 = 10584^2 + 5185^2 .

It is a cyclic number.

It is not a de Polignac number, because 138905281 - 2²⁵ = 105350849 is a prime.

It is a super-2 number, since 2×138905281² = 38589354179377922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 138905281.

It is not a weakly prime, because it can be changed into another prime (138906281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69452640 + 69452641.

It is an arithmetic number, because the mean of its divisors is an integer number (69452641).

Almost surely, 2^138905281 is an apocalyptic number.

It is an amenable number.

138905281 is a deficient number, since it is larger than the sum of its proper divisors (1).

138905281 is an equidigital number, since it uses as much as digits as its factorization.

138905281 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17280, while the sum is 37.

The square root of 138905281 is about 11785.8084576324. The cubic root of 138905281 is about 517.8924571644.

It can be divided in two parts, 13890528 and 1, that added together give a square (13890529 = 3727²).

The spelling of 138905281 in words is "one hundred thirty-eight million, nine hundred five thousand, two hundred eighty-one".