641798566966656 has 384 divisors, whose sum is σ = 2061943388144640. Its totient is φ = 189929081180160.

The previous prime is 641798566966597. The next prime is 641798566966771. The reversal of 641798566966656 is 656669665897146.

It is a tau number, because it is divible by the number of its divisors (384).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3289439601 + ... + 3289634703.

It is an arithmetic number, because the mean of its divisors is an integer number (5369644239960).

Almost surely, 2^{641798566966656} is an apocalyptic number.

641798566966656 is a gapful number since it is divisible by the number (66) 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 641798566966656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1030971694072320).

641798566966656 is an abundant number, since it is smaller than the sum of its proper divisors (1420144821177984).

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

641798566966656 is a wasteful number, since it uses less digits than its factorization.

641798566966656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201214 (or 201199 counting only the distinct ones).

The product of its digits is 126978969600, while the sum is 90.

The spelling of 641798566966656 in words is "six hundred forty-one trillion, seven hundred ninety-eight billion, five hundred sixty-six million, nine hundred sixty-six thousand, six hundred fifty-six".