666918278784 has 256 divisors, whose sum is σ = 2034711014400. Its totient is φ = 214829936640.

The previous prime is 666918278777. The next prime is 666918278801. The reversal of 666918278784 is 487872819666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 82812102 + ... + 82820154.

It is an arithmetic number, because the mean of its divisors is an integer number (7948089900).

Almost surely, 2^666918278784 is an apocalyptic number.

666918278784 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666918278784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1017355507200).

666918278784 is an abundant number, since it is smaller than the sum of its proper divisors (1367792735616).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666918278784 is a wasteful number, since it uses less digits than its factorization.

666918278784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8880 (or 8862 counting only the distinct ones).

The product of its digits is 390168576, while the sum is 72.

The spelling of 666918278784 in words is "six hundred sixty-six billion, nine hundred eighteen million, two hundred seventy-eight thousand, seven hundred eighty-four".