138770209 has 2 divisors, whose sum is σ = 138770210. Its totient is φ = 138770208.

The previous prime is 138770207. The next prime is 138770227. The reversal of 138770209 is 902077831.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 109307025 + 29463184 = 10455^2 + 5428^2 .

It is a cyclic number.

It is not a de Polignac number, because 138770209 - 2¹ = 138770207 is a prime.

Together with 138770207, it forms a pair of twin primes.

It is a zygodrome in base 13.

It is not a weakly prime, because it can be changed into another prime (138770207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69385104 + 69385105.

It is an arithmetic number, because the mean of its divisors is an integer number (69385105).

Almost surely, 2^138770209 is an apocalyptic number.

It is an amenable number.

138770209 is a deficient number, since it is larger than the sum of its proper divisors (1).

138770209 is an equidigital number, since it uses as much as digits as its factorization.

138770209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21168, while the sum is 37.

The square root of 138770209 is about 11780.0767824323. The cubic root of 138770209 is about 517.7245358878.

The spelling of 138770209 in words is "one hundred thirty-eight million, seven hundred seventy thousand, two hundred nine".