6664640400 has 720 divisors, whose sum is σ = 26769000960. Its totient is φ = 1520640000.

The previous prime is 6664640377. The next prime is 6664640417. The reversal of 6664640400 is 40464666.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (720).

It is a super-2 number, since 2×6664640400² = 88834863322624320000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 74883556 + ... + 74883644.

It is an arithmetic number, because the mean of its divisors is an integer number (37179168).

Almost surely, 2^6664640400 is an apocalyptic number.

6664640400 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 6664640400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13384500480).

6664640400 is an abundant number, since it is smaller than the sum of its proper divisors (20104360560).

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

6664640400 is a wasteful number, since it uses less digits than its factorization.

6664640400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216 (or 202 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 6664640400 is about 81637.2488512444. The cubic root of 6664640400 is about 1881.8813594467.

The spelling of 6664640400 in words is "six billion, six hundred sixty-four million, six hundred forty thousand, four hundred".