666768043821 has 24 divisors (see below), whose sum is σ = 981246599872. Its totient is φ = 402425020800.

The previous prime is 666768043801. The next prime is 666768043847. The reversal of 666768043821 is 128340867666.

It is not a de Polignac number, because 666768043821 - 2¹⁰ = 666768042797 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666768043801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3723361 + ... + 3898326.

Almost surely, 2^666768043821 is an apocalyptic number.

It is an amenable number.

666768043821 is a deficient number, since it is larger than the sum of its proper divisors (314478556051).

666768043821 is a wasteful number, since it uses less digits than its factorization.

666768043821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7621953 (or 7621942 counting only the distinct ones).

The product of its (nonzero) digits is 13934592, while the sum is 57.

The spelling of 666768043821 in words is "six hundred sixty-six billion, seven hundred sixty-eight million, forty-three thousand, eight hundred twenty-one".