138972989 has 2 divisors, whose sum is σ = 138972990. Its totient is φ = 138972988.

The previous prime is 138972971. The next prime is 138973013. The reversal of 138972989 is 989279831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 127125625 + 11847364 = 11275^2 + 3442^2 .

It is an emirp because it is prime and its reverse (989279831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138972989 - 2⁸ = 138972733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (138975989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69486494 + 69486495.

It is an arithmetic number, because the mean of its divisors is an integer number (69486495).

Almost surely, 2^138972989 is an apocalyptic number.

It is an amenable number.

138972989 is a deficient number, since it is larger than the sum of its proper divisors (1).

138972989 is an equidigital number, since it uses as much as digits as its factorization.

138972989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1959552, while the sum is 56.

The square root of 138972989 is about 11788.6805453367. The cubic root of 138972989 is about 517.9765906745.

The spelling of 138972989 in words is "one hundred thirty-eight million, nine hundred seventy-two thousand, nine hundred eighty-nine".