66613777326720 has 576 divisors, whose sum is σ = 249453642143160. Its totient is φ = 16372712079360.

The previous prime is 66613777326713. The next prime is 66613777326727. The reversal of 66613777326720 is 2762377731666.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (66613777326713) and next prime (66613777326727).

It can be written as a sum of positive squares in 12 ways, for example, as 3654122803776 + 62959654522944 = 1911576^2 + 7934712^2 .

It is a tau number, because it is divible by the number of its divisors (576).

It is not an unprimeable number, because it can be changed into a prime (66613777326727) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 655074280 + ... + 655175960.

Almost surely, 2^{66613777326720} is an apocalyptic number.

66613777326720 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 66613777326720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (124726821071580).

66613777326720 is an abundant number, since it is smaller than the sum of its proper divisors (182839864816440).

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

66613777326720 is a wasteful number, since it uses less digits than its factorization.

66613777326720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102405 (or 102377 counting only the distinct ones).

The product of its (nonzero) digits is 112021056, while the sum is 63.

The spelling of 66613777326720 in words is "sixty-six trillion, six hundred thirteen billion, seven hundred seventy-seven million, three hundred twenty-six thousand, seven hundred twenty".