666640042 has 32 divisors (see below), whose sum is σ = 1078686720. Its totient is φ = 308018880.

The previous prime is 666640031. The next prime is 666640043. The reversal of 666640042 is 240046666.

It is not an unprimeable number, because it can be changed into a prime (666640043) 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 15 ways as a sum of consecutive naturals, for example, 383808 + ... + 385540.

It is an arithmetic number, because the mean of its divisors is an integer number (33708960).

Almost surely, 2^666640042 is an apocalyptic number.

666640042 is a deficient number, since it is larger than the sum of its proper divisors (412046678).

666640042 is a wasteful number, since it uses less digits than its factorization.

666640042 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1998.

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 666640042 is about 25819.3733851153. The cubic root of 666640042 is about 873.5688351871.

The spelling of 666640042 in words is "six hundred sixty-six million, six hundred forty thousand, forty-two".