81289475904 has 1008 divisors, whose sum is σ = 293773677120. Its totient is φ = 19725189120.

The previous prime is 81289475881. The next prime is 81289475923. The reversal of 81289475904 is 40957498218.

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, 1890452907 + ... + 1890452949.

It is an arithmetic number, because the mean of its divisors is an integer number (291442140).

Almost surely, 2^81289475904 is an apocalyptic number.

81289475904 is a gapful number since it is divisible by the number (84) 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 81289475904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146886838560).

81289475904 is an abundant number, since it is smaller than the sum of its proper divisors (212484201216).

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

81289475904 is a wasteful number, since it uses less digits than its factorization.

81289475904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168 (or 138 counting only the distinct ones).

The product of its (nonzero) digits is 5806080, while the sum is 57.

The spelling of 81289475904 in words is "eighty-one billion, two hundred eighty-nine million, four hundred seventy-five thousand, nine hundred four".