138989281 has 2 divisors, whose sum is σ = 138989282. Its totient is φ = 138989280.

The previous prime is 138989233. The next prime is 138989317. The reversal of 138989281 is 182989831.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 99500625 + 39488656 = 9975^2 + 6284^2 .

It is a cyclic number.

It is not a de Polignac number, because 138989281 - 2¹⁹ = 138464993 is a prime.

It is a super-2 number, since 2×138989281² = 38636040465793922, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (138989581) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69494640 + 69494641.

It is an arithmetic number, because the mean of its divisors is an integer number (69494641).

Almost surely, 2^138989281 is an apocalyptic number.

It is an amenable number.

138989281 is a deficient number, since it is larger than the sum of its proper divisors (1).

138989281 is an equidigital number, since it uses as much as digits as its factorization.

138989281 is an evil number, because the sum of its binary digits is even.

The product of its digits is 248832, while the sum is 49.

The square root of 138989281 is about 11789.3715269305. The cubic root of 138989281 is about 517.9968309263.

The spelling of 138989281 in words is "one hundred thirty-eight million, nine hundred eighty-nine thousand, two hundred eighty-one".