139639309 has 18 divisors (see below), whose sum is σ = 152481374. Its totient is φ = 127818240.

The previous prime is 139639273. The next prime is 139639327. The reversal of 139639309 is 903936931.

It can be written as a sum of positive squares in 9 ways, for example, as 62252100 + 77387209 = 7890^2 + 8797^2 .

It is not a de Polignac number, because 139639309 - 2¹⁹ = 139115021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (139639349) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1568937 + ... + 1569025.

Almost surely, 2^139639309 is an apocalyptic number.

It is an amenable number.

139639309 is a deficient number, since it is larger than the sum of its proper divisors (12842065).

139639309 is an frugal number, since it uses more digits than its factorization.

139639309 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 118098, while the sum is 43.

The square root of 139639309 is about 11816.9077596468. The cubic root of 139639309 is about 518.8031014688.

The spelling of 139639309 in words is "one hundred thirty-nine million, six hundred thirty-nine thousand, three hundred nine".