139517909 has 2 divisors, whose sum is σ = 139517910. Its totient is φ = 139517908.

The previous prime is 139517899. The next prime is 139517933. The reversal of 139517909 is 909715931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 128482225 + 11035684 = 11335^2 + 3322^2 .

It is an emirp because it is prime and its reverse (909715931) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 139517909 - 2²⁴ = 122740693 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 139517909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139517509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69758954 + 69758955.

It is an arithmetic number, because the mean of its divisors is an integer number (69758955).

Almost surely, 2^139517909 is an apocalyptic number.

It is an amenable number.

139517909 is a deficient number, since it is larger than the sum of its proper divisors (1).

139517909 is an equidigital number, since it uses as much as digits as its factorization.

139517909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 76545, while the sum is 44.

The square root of 139517909 is about 11811.7699351113. The cubic root of 139517909 is about 518.6527117307.

The spelling of 139517909 in words is "one hundred thirty-nine million, five hundred seventeen thousand, nine hundred nine".