639138 has 16 divisors (see below), whose sum is σ = 1313280. Its totient is φ = 207216.

The previous prime is 639137. The next prime is 639143. The reversal of 639138 is 831936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1218 + ... + 1661.

It is an arithmetic number, because the mean of its divisors is an integer number (82080).

2⁶³⁹¹³⁸ is an apocalyptic number.

639138 is an abundant number, since it is smaller than the sum of its proper divisors (674142).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639138 is a wasteful number, since it uses less digits than its factorization.

639138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2921.

The product of its digits is 3888, while the sum is 30.

The square root of 639138 is about 799.4610684705. The cubic root of 639138 is about 86.1386801617.

It can be divided in two parts, 639 and 138, that added together give a palindrome (777).

The spelling of 639138 in words is "six hundred thirty-nine thousand, one hundred thirty-eight".