81091229197440 has 1024 divisors, whose sum is σ = 336875131699200. Its totient is φ = 16088503664640.

The previous prime is 81091229197399. The next prime is 81091229197543. The reversal of 81091229197440 is 4479192219018.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 1914358981 + ... + 1914401339.

It is an arithmetic number, because the mean of its divisors is an integer number (328979620800).

Almost surely, 2^{81091229197440} is an apocalyptic number.

81091229197440 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 81091229197440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (168437565849600).

81091229197440 is an abundant number, since it is smaller than the sum of its proper divisors (255783902501760).

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

81091229197440 is a wasteful number, since it uses less digits than its factorization.

81091229197440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42985 (or 42973 counting only the distinct ones).

The product of its (nonzero) digits is 2612736, while the sum is 57.

The spelling of 81091229197440 in words is "eighty-one trillion, ninety-one billion, two hundred twenty-nine million, one hundred ninety-seven thousand, four hundred forty".