81919118016 has 392 divisors, whose sum is σ = 259954135920. Its totient is φ = 25512247296.

The previous prime is 81919117991. The next prime is 81919118023. The reversal of 81919118016 is 61081191918.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 141973920 + ... + 141974496.

Almost surely, 2^81919118016 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 81919118016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129977067960).

81919118016 is an abundant number, since it is smaller than the sum of its proper divisors (178035017904).

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

81919118016 is a wasteful number, since it uses less digits than its factorization.

81919118016 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 803 (or 778 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 45.

The spelling of 81919118016 in words is "eighty-one billion, nine hundred nineteen million, one hundred eighteen thousand, sixteen".