6639638 has 4 divisors (see below), whose sum is σ = 9959460. Its totient is φ = 3319818.

The previous prime is 6639631. The next prime is 6639641. The reversal of 6639638 is 8369366.

It is a semiprime because it is the product of two primes.

It is a junction number, because it is equal to n+sod(n) for n = 6639595 and 6639604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6639631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1659908 + ... + 1659911.

It is an arithmetic number, because the mean of its divisors is an integer number (2489865).

Almost surely, 2^6639638 is an apocalyptic number.

6639638 is a deficient number, since it is larger than the sum of its proper divisors (3319822).

6639638 is a wasteful number, since it uses less digits than its factorization.

6639638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3319821.

The product of its digits is 139968, while the sum is 41.

The square root of 6639638 is about 2576.7495027651. The cubic root of 6639638 is about 187.9525117720.

It can be divided in two parts, 663 and 9638, that added together give a palindrome (10301).

The spelling of 6639638 in words is "six million, six hundred thirty-nine thousand, six hundred thirty-eight".