6643640 has 32 divisors (see below), whose sum is σ = 15316560. Its totient is φ = 2592000.

The previous prime is 6643633. The next prime is 6643649. The reversal of 6643640 is 463466.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6643649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 386 + ... + 3665.

Almost surely, 2^6643640 is an apocalyptic number.

It is an amenable number.

6643640 is an abundant number, since it is smaller than the sum of its proper divisors (8672920).

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

6643640 is a wasteful number, since it uses less digits than its factorization.

6643640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4103 (or 4099 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 29.

The square root of 6643640 is about 2577.5259455532. The cubic root of 6643640 is about 187.9902665853.

The spelling of 6643640 in words is "six million, six hundred forty-three thousand, six hundred forty".