666021321766 has 4 divisors (see below), whose sum is σ = 999031982652. Its totient is φ = 333010660882.

The previous prime is 666021321751. The next prime is 666021321799. The reversal of 666021321766 is 667123120666.

It is a semiprime because it is the product of two primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166505330440 + ... + 166505330443.

It is an arithmetic number, because the mean of its divisors is an integer number (249757995663).

Almost surely, 2^666021321766 is an apocalyptic number.

666021321766 is a deficient number, since it is larger than the sum of its proper divisors (333010660886).

666021321766 is a wasteful number, since it uses less digits than its factorization.

666021321766 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333010660885.

The product of its (nonzero) digits is 653184, while the sum is 46.

The spelling of 666021321766 in words is "six hundred sixty-six billion, twenty-one million, three hundred twenty-one thousand, seven hundred sixty-six".