138443281 has 2 divisors, whose sum is σ = 138443282. Its totient is φ = 138443280.

The previous prime is 138443267. The next prime is 138443287. The reversal of 138443281 is 182344831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 107972881 + 30470400 = 10391^2 + 5520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-138443281 is a prime.

It is a super-2 number, since 2×138443281² = 38333084108089922, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (138443287) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69221640 + 69221641.

It is an arithmetic number, because the mean of its divisors is an integer number (69221641).

Almost surely, 2^138443281 is an apocalyptic number.

It is an amenable number.

138443281 is a deficient number, since it is larger than the sum of its proper divisors (1).

138443281 is an equidigital number, since it uses as much as digits as its factorization.

138443281 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18432, while the sum is 34.

The square root of 138443281 is about 11766.1922897767. The cubic root of 138443281 is about 517.3176480285.

The spelling of 138443281 in words is "one hundred thirty-eight million, four hundred forty-three thousand, two hundred eighty-one".