81951097984 has 256 divisors, whose sum is σ = 195587758080. Its totient is φ = 33480179712.

The previous prime is 81951097961. The next prime is 81951097997. The reversal of 81951097984 is 48979015918.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 424616992 + ... + 424617184.

It is an arithmetic number, because the mean of its divisors is an integer number (764014680).

Almost surely, 2^81951097984 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 81951097984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97793879040).

81951097984 is an abundant number, since it is smaller than the sum of its proper divisors (113636660096).

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

81951097984 is a wasteful number, since it uses less digits than its factorization.

81951097984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 467 (or 455 counting only the distinct ones).

The product of its (nonzero) digits is 6531840, while the sum is 61.

The spelling of 81951097984 in words is "eighty-one billion, nine hundred fifty-one million, ninety-seven thousand, nine hundred eighty-four".