138472639 has 4 divisors (see below), whose sum is σ = 138715720. Its totient is φ = 138229560.

The previous prime is 138472637. The next prime is 138472643. The reversal of 138472639 is 936274831.

138472639 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 an emirpimes, since its reverse is a distinct semiprime: 936274831 = 29 ⋅32285339.

It is a cyclic number.

It is not a de Polignac number, because 138472639 - 2¹ = 138472637 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 138472595 and 138472604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (138472637) 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, 120684 + ... + 121825.

It is an arithmetic number, because the mean of its divisors is an integer number (34678930).

Almost surely, 2^138472639 is an apocalyptic number.

138472639 is a deficient number, since it is larger than the sum of its proper divisors (243081).

138472639 is an equidigital number, since it uses as much as digits as its factorization.

138472639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 243080.

The product of its digits is 217728, while the sum is 43.

The square root of 138472639 is about 11767.4397810229. The cubic root of 138472639 is about 517.3542125527.

The spelling of 138472639 in words is "one hundred thirty-eight million, four hundred seventy-two thousand, six hundred thirty-nine".