138005209 has 2 divisors, whose sum is σ = 138005210. Its totient is φ = 138005208.

The previous prime is 138005173. The next prime is 138005213. The reversal of 138005209 is 902500831.

138005209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 111513600 + 26491609 = 10560^2 + 5147^2 .

It is an emirp because it is prime and its reverse (902500831) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 138005209 - 2¹³ = 137997017 is a prime.

It is a super-2 number, since 2×138005209² = 38090875422267362, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (138005239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69002604 + 69002605.

It is an arithmetic number, because the mean of its divisors is an integer number (69002605).

Almost surely, 2^138005209 is an apocalyptic number.

It is an amenable number.

138005209 is a deficient number, since it is larger than the sum of its proper divisors (1).

138005209 is an equidigital number, since it uses as much as digits as its factorization.

138005209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 138005209 is about 11747.5618321420. The cubic root of 138005209 is about 516.7714271558.

The spelling of 138005209 in words is "one hundred thirty-eight million, five thousand, two hundred nine".