138920909 has 4 divisors (see below), whose sum is σ = 139920480. Its totient is φ = 137921340.

The previous prime is 138920893. The next prime is 138920921. The reversal of 138920909 is 909029831.

138920909 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 138920909 - 2⁴ = 138920893 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138920959) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 499577 + ... + 499854.

It is an arithmetic number, because the mean of its divisors is an integer number (34980120).

Almost surely, 2^138920909 is an apocalyptic number.

It is an amenable number.

138920909 is a deficient number, since it is larger than the sum of its proper divisors (999571).

138920909 is an equidigital number, since it uses as much as digits as its factorization.

138920909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 999570.

The product of its (nonzero) digits is 34992, while the sum is 41.

The square root of 138920909 is about 11786.4714397482. The cubic root of 138920909 is about 517.9118788397.

The spelling of 138920909 in words is "one hundred thirty-eight million, nine hundred twenty thousand, nine hundred nine".