66720847680 has 168 divisors, whose sum is σ = 229588310952. Its totient is φ = 17784754176.

The previous prime is 66720847673. The next prime is 66720847691. The reversal of 66720847680 is 8674802766.

It can be written as a sum of positive squares in 4 ways, for example, as 8156736 + 66712690944 = 2856^2 + 258288^2 .

It is a super-2 number, since 2×66720847680² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11969374 + ... + 11974946.

It is an arithmetic number, because the mean of its divisors is an integer number (1366597089).

Almost surely, 2^66720847680 is an apocalyptic number.

66720847680 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 66720847680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114794155476).

66720847680 is an abundant number, since it is smaller than the sum of its proper divisors (162867463272).

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

66720847680 is a wasteful number, since it uses less digits than its factorization.

66720847680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9753 (or 9740 counting only the distinct ones).

The product of its (nonzero) digits is 5419008, while the sum is 54.

The spelling of 66720847680 in words is "sixty-six billion, seven hundred twenty million, eight hundred forty-seven thousand, six hundred eighty".