666778596121 has 4 divisors (see below), whose sum is σ = 727394832144. Its totient is φ = 606162360100.

The previous prime is 666778596053. The next prime is 666778596131. The reversal of 666778596121 is 121695877666.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 666778596121 - 2¹⁹ = 666778071833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666778596131) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 30308117995 + ... + 30308118016.

It is an arithmetic number, because the mean of its divisors is an integer number (181848708036).

Almost surely, 2^666778596121 is an apocalyptic number.

It is an amenable number.

666778596121 is a deficient number, since it is larger than the sum of its proper divisors (60616236023).

666778596121 is a wasteful number, since it uses less digits than its factorization.

666778596121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 60616236022.

The product of its digits is 45722880, while the sum is 64.

The spelling of 666778596121 in words is "six hundred sixty-six billion, seven hundred seventy-eight million, five hundred ninety-six thousand, one hundred twenty-one".