66521956320 has 480 divisors, whose sum is σ = 243428613120. Its totient is φ = 17096002560.

The previous prime is 66521956313. The next prime is 66521956321. The reversal of 66521956320 is 2365912566.

66521956320 is a `hidden beast` number, since 6 + 6 + 5 + 2 + 1 + 9 + 5 + 632 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66521956321) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 44024365 + ... + 44025875.

It is an arithmetic number, because the mean of its divisors is an integer number (507142944).

Almost surely, 2^66521956320 is an apocalyptic number.

66521956320 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 66521956320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (121714306560).

66521956320 is an abundant number, since it is smaller than the sum of its proper divisors (176906656800).

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

66521956320 is a wasteful number, since it uses less digits than its factorization.

66521956320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1660 (or 1643 counting only the distinct ones).

The product of its (nonzero) digits is 583200, while the sum is 45.

The spelling of 66521956320 in words is "sixty-six billion, five hundred twenty-one million, nine hundred fifty-six thousand, three hundred twenty".