6643516840 has 64 divisors (see below), whose sum is σ = 15204087360. Its totient is φ = 2612113920.

The previous prime is 6643516837. The next prime is 6643516849. The reversal of 6643516840 is 486153466.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (6643516849) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 892735 + ... + 900145.

It is an arithmetic number, because the mean of its divisors is an integer number (237563865).

Almost surely, 2^6643516840 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 6643516840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7602043680).

6643516840 is an abundant number, since it is smaller than the sum of its proper divisors (8560570520).

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

6643516840 is a wasteful number, since it uses less digits than its factorization.

6643516840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7802 (or 7798 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 43.

The square root of 6643516840 is about 81507.7716539963. The cubic root of 6643516840 is about 1879.8910492166.

The spelling of 6643516840 in words is "six billion, six hundred forty-three million, five hundred sixteen thousand, eight hundred forty".