81641289600 has 1152 divisors, whose sum is σ = 338108359680. Its totient is φ = 18579456000.

The previous prime is 81641289599. The next prime is 81641289619. The reversal of 81641289600 is 698214618.

81641289600 is a `hidden beast` number, since 8 + 16 + 4 + 1 + 28 + 9 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 642844737 + ... + 642844863.

It is an arithmetic number, because the mean of its divisors is an integer number (293496840).

Almost surely, 2^81641289600 is an apocalyptic number.

81641289600 is a gapful number since it is divisible by the number (80) 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 81641289600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (169054179840).

81641289600 is an abundant number, since it is smaller than the sum of its proper divisors (256467070080).

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

81641289600 is a wasteful number, since it uses less digits than its factorization.

81641289600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288 (or 268 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 81641289600 in words is "eighty-one billion, six hundred forty-one million, two hundred eighty-nine thousand, six hundred".