81397847808 has 144 divisors (see below), whose sum is σ = 240869129760. Its totient is φ = 27114430464.

The previous prime is 81397847761. The next prime is 81397847819. The reversal of 81397847808 is 80874879318.

It is a tau number, because it is divible by the number of its divisors (144).

It is a congruent number.

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, 13800316 + ... + 13806212.

It is an arithmetic number, because the mean of its divisors is an integer number (1672702290).

Almost surely, 2^81397847808 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 81397847808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (120434564880).

81397847808 is an abundant number, since it is smaller than the sum of its proper divisors (159471281952).

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

81397847808 is a wasteful number, since it uses less digits than its factorization.

81397847808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7919 (or 7899 counting only the distinct ones).

The product of its (nonzero) digits is 21676032, while the sum is 63.

The spelling of 81397847808 in words is "eighty-one billion, three hundred ninety-seven million, eight hundred forty-seven thousand, eight hundred eight".