640564666 has 8 divisors (see below), whose sum is σ = 1098110880. Its totient is φ = 274527708.

The previous prime is 640564657. The next prime is 640564669. The reversal of 640564666 is 666465046.

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 (640564669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22877296 + ... + 22877323.

It is an arithmetic number, because the mean of its divisors is an integer number (137263860).

Almost surely, 2^640564666 is an apocalyptic number.

640564666 is a deficient number, since it is larger than the sum of its proper divisors (457546214).

640564666 is a wasteful number, since it uses less digits than its factorization.

640564666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45754628.

The product of its (nonzero) digits is 622080, while the sum is 43.

The square root of 640564666 is about 25309.3790125321. The cubic root of 640564666 is about 862.0272465158.

The spelling of 640564666 in words is "six hundred forty million, five hundred sixty-four thousand, six hundred sixty-six".