138684905 has 4 divisors (see below), whose sum is σ = 166421892. Its totient is φ = 110947920.

The previous prime is 138684901. The next prime is 138684907. The reversal of 138684905 is 509486831.

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 97673689 + 41011216 = 9883^2 + 6404^2 .

It is not a de Polignac number, because 138684905 - 2² = 138684901 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (138684901) 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 3 ways as a sum of consecutive naturals, for example, 13868486 + ... + 13868495.

It is an arithmetic number, because the mean of its divisors is an integer number (41605473).

Almost surely, 2^138684905 is an apocalyptic number.

It is an amenable number.

138684905 is a deficient number, since it is larger than the sum of its proper divisors (27736987).

138684905 is an equidigital number, since it uses as much as digits as its factorization.

138684905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27736986.

The product of its (nonzero) digits is 207360, while the sum is 44.

The square root of 138684905 is about 11776.4555363658. The cubic root of 138684905 is about 517.6184299576.

The spelling of 138684905 in words is "one hundred thirty-eight million, six hundred eighty-four thousand, nine hundred five".