81947397267456 has 224 divisors, whose sum is σ = 251261372617728. Its totient is φ = 23269892751360.

The previous prime is 81947397267391. The next prime is 81947397267469. The reversal of 81947397267456 is 65476279374918.

It is a tau number, because it is divible by the number of its divisors (224).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26580021 + ... + 29502411.

Almost surely, 2^{81947397267456} 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 81947397267456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125630686308864).

81947397267456 is an abundant number, since it is smaller than the sum of its proper divisors (169313975350272).

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

81947397267456 is a wasteful number, since it uses less digits than its factorization.

81947397267456 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2922590 (or 2922566 counting only the distinct ones).

The product of its digits is 3840721920, while the sum is 78.

The spelling of 81947397267456 in words is "eighty-one trillion, nine hundred forty-seven billion, three hundred ninety-seven million, two hundred sixty-seven thousand, four hundred fifty-six".