138539905 has 12 divisors (see below), whose sum is σ = 193390740. Its totient is φ = 94998624.

The previous prime is 138539903. The next prime is 138539917. The reversal of 138539905 is 509935831.

It can be written as a sum of positive squares in 2 ways, for example, as 24285184 + 114254721 = 4928^2 + 10689^2 .

It is not a de Polignac number, because 138539905 - 2¹ = 138539903 is a prime.

It is not an unprimeable number, because it can be changed into a prime (138539903) 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 11 ways as a sum of consecutive naturals, for example, 282490 + ... + 282979.

It is an arithmetic number, because the mean of its divisors is an integer number (16115895).

Almost surely, 2^138539905 is an apocalyptic number.

It is an amenable number.

138539905 is a deficient number, since it is larger than the sum of its proper divisors (54850835).

138539905 is an equidigital number, since it uses as much as digits as its factorization.

138539905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 565488 (or 565481 counting only the distinct ones).

The product of its (nonzero) digits is 145800, while the sum is 43.

The square root of 138539905 is about 11770.2975748279. The cubic root of 138539905 is about 517.4379708923.

The spelling of 138539905 in words is "one hundred thirty-eight million, five hundred thirty-nine thousand, nine hundred five".