661172418480000 has 640 divisors, whose sum is σ = 2539859084928000. Its totient is φ = 149212118016000.

The previous prime is 661172418479819. The next prime is 661172418480029. The reversal of 661172418480000 is 84814271166.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 130229146 + ... + 135210854.

It is an arithmetic number, because the mean of its divisors is an integer number (3968529820200).

Almost surely, 2^{661172418480000} is an apocalyptic number.

661172418480000 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 661172418480000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1269929542464000).

661172418480000 is an abundant number, since it is smaller than the sum of its proper divisors (1878686666448000).

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

661172418480000 is an equidigital number, since it uses as much as digits as its factorization.

661172418480000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4981832 (or 4981805 counting only the distinct ones).

The product of its (nonzero) digits is 516096, while the sum is 48.

The spelling of 661172418480000 in words is "six hundred sixty-one trillion, one hundred seventy-two billion, four hundred eighteen million, four hundred eighty thousand".