666816800 has 144 divisors (see below), whose sum is σ = 1773839592. Its totient is φ = 243302400.

The previous prime is 666816793. The next prime is 666816809. The reversal of 666816800 is 8618666.

666816800 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 12 ways, for example, as 23078416 + 643738384 = 4804^2 + 25372^2 .

It is not an unprimeable number, because it can be changed into a prime (666816809) 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, 1008470 + ... + 1009130.

Almost surely, 2^666816800 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666816800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (886919796).

666816800 is an abundant number, since it is smaller than the sum of its proper divisors (1107022792).

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

666816800 is a wasteful number, since it uses less digits than its factorization.

666816800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 791 (or 778 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 41.

The square root of 666816800 is about 25822.7961305510. The cubic root of 666816800 is about 873.6460365878.

The spelling of 666816800 in words is "six hundred sixty-six million, eight hundred sixteen thousand, eight hundred".