81641000177856 has 1344 divisors, whose sum is σ = 299286401111040. Its totient is φ = 21365949726720.

The previous prime is 81641000177851. The next prime is 81641000177887. The reversal of 81641000177856 is 65877100014618.

81641000177856 is a `hidden beast` number, since 8 + 1 + 6 + 410 + 0 + 0 + 177 + 8 + 56 = 666.

It is a tau number, because it is divible by the number of its divisors (1344).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (81641000177851) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 20684315275 + ... + 20684319221.

It is an arithmetic number, because the mean of its divisors is an integer number (222683334160).

Almost surely, 2^{81641000177856} 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 81641000177856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149643200555520).

81641000177856 is an abundant number, since it is smaller than the sum of its proper divisors (217645400933184).

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

81641000177856 is a wasteful number, since it uses less digits than its factorization.

81641000177856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4167 (or 4134 counting only the distinct ones).

The product of its (nonzero) digits is 2257920, while the sum is 54.

The spelling of 81641000177856 in words is "eighty-one trillion, six hundred forty-one billion, one hundred seventy-seven thousand, eight hundred fifty-six".