81129371904 has 576 divisors, whose sum is σ = 281474170880. Its totient is φ = 22856214528.

The previous prime is 81129371891. The next prime is 81129371909. The reversal of 81129371904 is 40917392118.

It is a tau number, because it is divible by the number of its divisors (576).

It is a self number, because there is not a number n which added to its sum of digits gives 81129371904.

It is not an unprimeable number, because it can be changed into a prime (81129371909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 497726127 + ... + 497726289.

Almost surely, 2^81129371904 is an apocalyptic number.

81129371904 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 81129371904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140737085440).

81129371904 is an abundant number, since it is smaller than the sum of its proper divisors (200344798976).

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

81129371904 is an equidigital number, since it uses as much as digits as its factorization.

81129371904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 334 (or 302 counting only the distinct ones).

The product of its (nonzero) digits is 108864, while the sum is 45.

The spelling of 81129371904 in words is "eighty-one billion, one hundred twenty-nine million, three hundred seventy-one thousand, nine hundred four".