138509409 has 8 divisors (see below), whose sum is σ = 184795072. Its totient is φ = 92281680.

The previous prime is 138509401. The next prime is 138509417. The reversal of 138509409 is 904905831.

It is an interprime number because it is at equal distance from previous prime (138509401) and next prime (138509417).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 138509409 - 2³ = 138509401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138509401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8557 + ... + 18714.

It is an arithmetic number, because the mean of its divisors is an integer number (23099384).

Almost surely, 2^138509409 is an apocalyptic number.

It is an amenable number.

138509409 is a deficient number, since it is larger than the sum of its proper divisors (46285663).

138509409 is a wasteful number, since it uses less digits than its factorization.

138509409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28967.

The product of its (nonzero) digits is 38880, while the sum is 39.

The square root of 138509409 is about 11769.0020392555. The cubic root of 138509409 is about 517.4000012153.

The spelling of 138509409 in words is "one hundred thirty-eight million, five hundred nine thousand, four hundred nine".