81131407488 has 128 divisors (see below), whose sum is σ = 239875521600. Its totient is φ = 26995783680.

The previous prime is 81131407421. The next prime is 81131407493. The reversal of 81131407488 is 88470413118.

It is a tau number, because it is divible by the number of its divisors (128).

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, 1952820 + ... + 1993932.

Almost surely, 2^81131407488 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 81131407488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119937760800).

81131407488 is an abundant number, since it is smaller than the sum of its proper divisors (158744114112).

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

81131407488 is a wasteful number, since it uses less digits than its factorization.

81131407488 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41707 (or 41689 counting only the distinct ones).

The product of its (nonzero) digits is 172032, while the sum is 45.

The spelling of 81131407488 in words is "eighty-one billion, one hundred thirty-one million, four hundred seven thousand, four hundred eighty-eight".