138668993 has 2 divisors, whose sum is σ = 138668994. Its totient is φ = 138668992.

The previous prime is 138668977. The next prime is 138669019. The reversal of 138668993 is 399866831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73753744 + 64915249 = 8588^2 + 8057^2 .

It is a cyclic number.

It is not a de Polignac number, because 138668993 - 2⁴ = 138668977 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (138668903) 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, 69334496 + 69334497.

It is an arithmetic number, because the mean of its divisors is an integer number (69334497).

Almost surely, 2^138668993 is an apocalyptic number.

It is an amenable number.

138668993 is a deficient number, since it is larger than the sum of its proper divisors (1).

138668993 is an equidigital number, since it uses as much as digits as its factorization.

138668993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1679616, while the sum is 53.

The square root of 138668993 is about 11775.7799317073. The cubic root of 138668993 is about 517.5986328992.

The spelling of 138668993 in words is "one hundred thirty-eight million, six hundred sixty-eight thousand, nine hundred ninety-three".