139979509 has 2 divisors, whose sum is σ = 139979510. Its totient is φ = 139979508.

The previous prime is 139979503. The next prime is 139979531. The reversal of 139979509 is 905979931.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 128890609 + 11088900 = 11353^2 + 3330^2 .

It is a cyclic number.

It is not a de Polignac number, because 139979509 - 2¹⁷ = 139848437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (139979503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 69989754 + 69989755.

It is an arithmetic number, because the mean of its divisors is an integer number (69989755).

Almost surely, 2^139979509 is an apocalyptic number.

It is an amenable number.

139979509 is a deficient number, since it is larger than the sum of its proper divisors (1).

139979509 is an equidigital number, since it uses as much as digits as its factorization.

139979509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 688905, while the sum is 52.

The square root of 139979509 is about 11831.2936317209. The cubic root of 139979509 is about 519.2240757594.

It can be divided in two parts, 1399 and 79509, that added together give a palindrome (80908).

The spelling of 139979509 in words is "one hundred thirty-nine million, nine hundred seventy-nine thousand, five hundred nine".