6439940 has 96 divisors (see below), whose sum is σ = 16257024. Its totient is φ = 2119680.

The previous prime is 6439933. The next prime is 6439949. The reversal of 6439940 is 499346.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 6439940.

It is not an unprimeable number, because it can be changed into a prime (6439949) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 136997 + ... + 137043.

It is an arithmetic number, because the mean of its divisors is an integer number (169344).

Almost surely, 2^6439940 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6439940, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8128512).

6439940 is an abundant number, since it is smaller than the sum of its proper divisors (9817084).

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

6439940 is a wasteful number, since it uses less digits than its factorization.

6439940 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117 (or 115 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 35.

The square root of 6439940 is about 2537.7036864063. The cubic root of 6439940 is about 186.0489715736.

It can be divided in two parts, 64 and 39940, that added together give a palindrome (40004).

The spelling of 6439940 in words is "six million, four hundred thirty-nine thousand, nine hundred forty".