66321446400 has 720 divisors, whose sum is σ = 261213638400. Its totient is φ = 15936307200.

The previous prime is 66321446369. The next prime is 66321446423. The reversal of 66321446400 is 464412366.

66321446400 is a `hidden beast` number, since 6 + 6 + 3 + 2 + 1 + 4 + 4 + 640 + 0 = 666.

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

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 252172669 + ... + 252172931.

It is an arithmetic number, because the mean of its divisors is an integer number (362796720).

Almost surely, 2^66321446400 is an apocalyptic number.

66321446400 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 66321446400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (130606819200).

66321446400 is an abundant number, since it is smaller than the sum of its proper divisors (194892192000).

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

66321446400 is a wasteful number, since it uses less digits than its factorization.

66321446400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507 (or 483 counting only the distinct ones).

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

Adding to 66321446400 its reverse (464412366), we get a palindrome (66785858766).

The spelling of 66321446400 in words is "sixty-six billion, three hundred twenty-one million, four hundred forty-six thousand, four hundred".