66217765728 has 192 divisors, whose sum is σ = 185138170560. Its totient is φ = 20683579392.

The previous prime is 66217765727. The next prime is 66217765753. The reversal of 66217765728 is 82756771266.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66217765727) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 75504426 + ... + 75505302.

It is an arithmetic number, because the mean of its divisors is an integer number (964261305).

Almost surely, 2^66217765728 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 66217765728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92569085280).

66217765728 is an abundant number, since it is smaller than the sum of its proper divisors (118920404832).

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

66217765728 is a wasteful number, since it uses less digits than its factorization.

66217765728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1689 (or 1681 counting only the distinct ones).

The product of its digits is 11854080, while the sum is 57.

The spelling of 66217765728 in words is "sixty-six billion, two hundred seventeen million, seven hundred sixty-five thousand, seven hundred twenty-eight".