6656640 has 64 divisors (see below), whose sum is σ = 21224160. Its totient is φ = 1774592.

The previous prime is 6656627. The next prime is 6656647. The reversal of 6656640 is 466566.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (6656647) 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, 187 + ... + 3653.

Almost surely, 2^6656640 is an apocalyptic number.

6656640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6656640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10612080).

6656640 is an abundant number, since it is smaller than the sum of its proper divisors (14567520).

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

6656640 is a wasteful number, since it uses less digits than its factorization.

6656640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3489 (or 3477 counting only the distinct ones).

The product of its (nonzero) digits is 25920, while the sum is 33.

The square root of 6656640 is about 2580.0465112087. The cubic root of 6656640 is about 188.1128038877.

The spelling of 6656640 in words is "six million, six hundred fifty-six thousand, six hundred forty".