66645541376720 has 80 divisors (see below), whose sum is σ = 156875906174400. Its totient is φ = 26327268068352.

The previous prime is 66645541376719. The next prime is 66645541376747. The reversal of 66645541376720 is 2767314554666.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16061972 + ... + 19780748.

It is an arithmetic number, because the mean of its divisors is an integer number (1960948827180).

Almost surely, 2^{66645541376720} 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 66645541376720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (78437953087200).

66645541376720 is an abundant number, since it is smaller than the sum of its proper divisors (90230364797680).

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

66645541376720 is a wasteful number, since it uses less digits than its factorization.

66645541376720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3721572 (or 3721566 counting only the distinct ones).

The product of its (nonzero) digits is 152409600, while the sum is 62.

The spelling of 66645541376720 in words is "sixty-six trillion, six hundred forty-five billion, five hundred forty-one million, three hundred seventy-six thousand, seven hundred twenty".