139509709 has 2 divisors, whose sum is σ = 139509710. Its totient is φ = 139509708.

The previous prime is 139509659. The next prime is 139509731. The reversal of 139509709 is 907905931.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 138062500 + 1447209 = 11750^2 + 1203^2 .

It is a cyclic number.

It is not a de Polignac number, because 139509709 - 2¹⁵ = 139476941 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139509739) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69754854 + 69754855.

It is an arithmetic number, because the mean of its divisors is an integer number (69754855).

Almost surely, 2^139509709 is an apocalyptic number.

It is an amenable number.

139509709 is a deficient number, since it is larger than the sum of its proper divisors (1).

139509709 is an equidigital number, since it uses as much as digits as its factorization.

139509709 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 43.

The square root of 139509709 is about 11811.4228186108. The cubic root of 139509709 is about 518.6425504651.

The spelling of 139509709 in words is "one hundred thirty-nine million, five hundred nine thousand, seven hundred nine".