664206666 has 16 divisors (see below), whose sum is σ = 1333212384. Its totient is φ = 220602384.

The previous prime is 664206661. The next prime is 664206667. The reversal of 664206666 is 666602466.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (664206661) 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, 198160 + ... + 201483.

It is an arithmetic number, because the mean of its divisors is an integer number (83325774).

Almost surely, 2^664206666 is an apocalyptic number.

664206666 is an abundant number, since it is smaller than the sum of its proper divisors (669005718).

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

664206666 is a wasteful number, since it uses less digits than its factorization.

664206666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 399925.

The product of its (nonzero) digits is 373248, while the sum is 42.

The square root of 664206666 is about 25772.2072395827. The cubic root of 664206666 is about 872.5046361168.

The spelling of 664206666 in words is "six hundred sixty-four million, two hundred six thousand, six hundred sixty-six".