138090809 has 4 divisors (see below), whose sum is σ = 138238500. Its totient is φ = 137943120.

The previous prime is 138090793. The next prime is 138090817. The reversal of 138090809 is 908090831.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48372025 + 89718784 = 6955^2 + 9472^2 .

It is a cyclic number.

It is not a de Polignac number, because 138090809 - 2⁴ = 138090793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138090839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72434 + ... + 74315.

It is an arithmetic number, because the mean of its divisors is an integer number (34559625).

Almost surely, 2^138090809 is an apocalyptic number.

It is an amenable number.

138090809 is a deficient number, since it is larger than the sum of its proper divisors (147691).

138090809 is an equidigital number, since it uses as much as digits as its factorization.

138090809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147690.

The product of its (nonzero) digits is 15552, while the sum is 38.

The square root of 138090809 is about 11751.2045765530. The cubic root of 138090809 is about 516.8782503974.

The spelling of 138090809 in words is "one hundred thirty-eight million, ninety thousand, eight hundred nine".