138928809 has 16 divisors (see below), whose sum is σ = 193564800. Its totient is φ = 88467456.

The previous prime is 138928807. The next prime is 138928831. The reversal of 138928809 is 908829831.

It is a happy number.

It is not a de Polignac number, because 138928809 - 2¹ = 138928807 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138928807) 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 15 ways as a sum of consecutive naturals, for example, 96507 + ... + 97935.

It is an arithmetic number, because the mean of its divisors is an integer number (12097800).

Almost surely, 2^138928809 is an apocalyptic number.

It is an amenable number.

138928809 is a deficient number, since it is larger than the sum of its proper divisors (54635991).

138928809 is a wasteful number, since it uses less digits than its factorization.

138928809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2864.

The product of its (nonzero) digits is 248832, while the sum is 48.

The square root of 138928809 is about 11786.8065649692. The cubic root of 138928809 is about 517.9216959995.

The spelling of 138928809 in words is "one hundred thirty-eight million, nine hundred twenty-eight thousand, eight hundred nine".