665821600 has 72 divisors (see below), whose sum is σ = 1631333088. Its totient is φ = 265363200.

The previous prime is 665821573. The next prime is 665821661. The reversal of 665821600 is 6128566.

665821600 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 244245 + ... + 246955.

It is an arithmetic number, because the mean of its divisors is an integer number (22657404).

Almost surely, 2^665821600 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 665821600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (815666544).

665821600 is an abundant number, since it is smaller than the sum of its proper divisors (965511488).

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

665821600 is a wasteful number, since it uses less digits than its factorization.

665821600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3038 (or 3025 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 34.

The square root of 665821600 is about 25803.5191398383. The cubic root of 665821600 is about 873.2111917965.

The spelling of 665821600 in words is "six hundred sixty-five million, eight hundred twenty-one thousand, six hundred".