6640668 has 18 divisors (see below), whose sum is σ = 16786224. Its totient is φ = 2213544.

The previous prime is 6640663. The next prime is 6640679. The reversal of 6640668 is 8660466.

6640668 = T₁₃₂ + T₁₃₃ + ... + T₃₄₇.

6640668 is a `hidden beast` number, since 6 + 640 + 6 + 6 + 8 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 184463 = 6640668 / (6 + 6 + 4 + 0 + 6 + 6 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640663) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 92196 + ... + 92267.

It is an arithmetic number, because the mean of its divisors is an integer number (932568).

Almost surely, 2^6640668 is an apocalyptic number.

It is an amenable number.

6640668 is an abundant number, since it is smaller than the sum of its proper divisors (10145556).

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

6640668 is a wasteful number, since it uses less digits than its factorization.

6640668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 184473 (or 184468 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 36.

The square root of 6640668 is about 2576.9493592230. The cubic root of 6640668 is about 187.9622302274.

The spelling of 6640668 in words is "six million, six hundred forty thousand, six hundred sixty-eight".