6640666 has 8 divisors (see below), whose sum is σ = 9981684. Its totient is φ = 3313440.

The previous prime is 6640663. The next prime is 6640679. The reversal of 6640666 is 6660466.

It can be written as a sum of positive squares in 2 ways, for example, as 6610041 + 30625 = 2571^2 + 175^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

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 3 ways as a sum of consecutive naturals, for example, 2145 + ... + 4228.

Almost surely, 2^6640666 is an apocalyptic number.

6640666 is a deficient number, since it is larger than the sum of its proper divisors (3341018).

6640666 is a wasteful number, since it uses less digits than its factorization.

6640666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6896.

The product of its (nonzero) digits is 31104, while the sum is 34.

The square root of 6640666 is about 2576.9489711673. The cubic root of 6640666 is about 187.9622113576.

The spelling of 6640666 in words is "six million, six hundred forty thousand, six hundred sixty-six".