6666978880 has 56 divisors (see below), whose sum is σ = 15892427448. Its totient is φ = 2663989248.

The previous prime is 6666978863. The next prime is 6666978883. The reversal of 6666978880 is 888796666.

It can be written as a sum of positive squares in 4 ways, for example, as 1942341184 + 4724637696 = 44072^2 + 68736^2 .

It is a Harshad number since it is a multiple of its sum of digits (64).

It is not an unprimeable number, because it can be changed into a prime (6666978883) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 308592 + ... + 329488.

Almost surely, 2^6666978880 is an apocalyptic number.

It is an amenable number.

6666978880 is an abundant number, since it is smaller than the sum of its proper divisors (9225448568).

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

6666978880 is a wasteful number, since it uses less digits than its factorization.

6666978880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21911 (or 21901 counting only the distinct ones).

The product of its (nonzero) digits is 41803776, while the sum is 64.

The square root of 6666978880 is about 81651.5699787824. The cubic root of 6666978880 is about 1882.1014377030.

The spelling of 6666978880 in words is "six billion, six hundred sixty-six million, nine hundred seventy-eight thousand, eight hundred eighty".