81218958912 has 336 divisors, whose sum is σ = 301606264960. Its totient is φ = 20292747264.

The previous prime is 81218958901. The next prime is 81218958949. The reversal of 81218958912 is 21985981218.

It is a tau number, because it is divible by the number of its divisors (336).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 955128 + ... + 1036680.

Almost surely, 2^81218958912 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 81218958912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150803132480).

81218958912 is an abundant number, since it is smaller than the sum of its proper divisors (220387306048).

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

81218958912 is a wasteful number, since it uses less digits than its factorization.

81218958912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81610 (or 81597 counting only the distinct ones).

The product of its digits is 829440, while the sum is 54.

The spelling of 81218958912 in words is "eighty-one billion, two hundred eighteen million, nine hundred fifty-eight thousand, nine hundred twelve".