6666978780 has 960 divisors, whose sum is σ = 28686873600. Its totient is φ = 1254113280.

The previous prime is 6666978749. The next prime is 6666978803. The reversal of 6666978780 is 878796666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 319 ways as a sum of consecutive naturals, for example, 68731692 + ... + 68731788.

It is an arithmetic number, because the mean of its divisors is an integer number (29882160).

Almost surely, 2^6666978780 is an apocalyptic number.

6666978780 is a gapful number since it is divisible by the number (60) 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 6666978780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14343436800).

6666978780 is an abundant number, since it is smaller than the sum of its proper divisors (22019894820).

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

6666978780 is a wasteful number, since it uses less digits than its factorization.

6666978780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184 (or 173 counting only the distinct ones).

The product of its (nonzero) digits is 36578304, while the sum is 63.

The square root of 6666978780 is about 81651.5693664243. The cubic root of 6666978780 is about 1882.1014282929.

The spelling of 6666978780 in words is "six billion, six hundred sixty-six million, nine hundred seventy-eight thousand, seven hundred eighty".