642118666 has 16 divisors (see below), whose sum is σ = 1101127104. Its totient is φ = 275105664.

The previous prime is 642118657. The next prime is 642118681. The reversal of 642118666 is 666811246.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 58101 + ... + 68263.

It is an arithmetic number, because the mean of its divisors is an integer number (68820444).

Almost surely, 2^642118666 is an apocalyptic number.

642118666 is a deficient number, since it is larger than the sum of its proper divisors (459008438).

642118666 is a wasteful number, since it uses less digits than its factorization.

642118666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14685.

The product of its digits is 82944, while the sum is 40.

The square root of 642118666 is about 25340.0604971654. The cubic root of 642118666 is about 862.7237718340.

The spelling of 642118666 in words is "six hundred forty-two million, one hundred eighteen thousand, six hundred sixty-six".