81891434327040 has 1584 divisors, whose sum is σ = 319786360897536. Its totient is φ = 19346787532800.

The previous prime is 81891434327023. The next prime is 81891434327051. The reversal of 81891434327040 is 4072343419818.

81891434327040 is a `hidden beast` number, since 8 + 18 + 9 + 14 + 343 + 270 + 4 + 0 = 666.

It is a super-2 number, since 2×81891434327040² (a number of 29 digits) contains 22 as substring.

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, 30659464905 + ... + 30659467575.

Almost surely, 2^{81891434327040} is an apocalyptic number.

81891434327040 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 81891434327040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (159893180448768).

81891434327040 is an abundant number, since it is smaller than the sum of its proper divisors (237894926570496).

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

81891434327040 is a wasteful number, since it uses less digits than its factorization.

81891434327040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2886 (or 2852 counting only the distinct ones).

The product of its (nonzero) digits is 4644864, while the sum is 54.

The spelling of 81891434327040 in words is "eighty-one trillion, eight hundred ninety-one billion, four hundred thirty-four million, three hundred twenty-seven thousand, forty".