81129030840 has 512 divisors, whose sum is σ = 318623155200. Its totient is φ = 18102528000.

The previous prime is 81129030767. The next prime is 81129030847. The reversal of 81129030840 is 4803092118.

It is a super-2 number, since 2×81129030840² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81129030795 and 81129030804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81129030847) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 83551555 + ... + 83552525.

It is an arithmetic number, because the mean of its divisors is an integer number (622310850).

Almost surely, 2^81129030840 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 81129030840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (159311577600).

81129030840 is an abundant number, since it is smaller than the sum of its proper divisors (237494124360).

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

81129030840 is a wasteful number, since it uses less digits than its factorization.

81129030840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1556 (or 1546 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

It can be divided in two parts, 81 and 129030840, that added together give a palindrome (129030921).

The spelling of 81129030840 in words is "eighty-one billion, one hundred twenty-nine million, thirty thousand, eight hundred forty".