81515919888 has 160 divisors (see below), whose sum is σ = 258125978880. Its totient is φ = 24470000640.

The previous prime is 81515919857. The next prime is 81515919923. The reversal of 81515919888 is 88891951518.

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, 53245 + ... + 407267.

It is an arithmetic number, because the mean of its divisors is an integer number (1613287368).

Almost surely, 2^81515919888 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 81515919888, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (129062989440).

81515919888 is an abundant number, since it is smaller than the sum of its proper divisors (176610058992).

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

81515919888 is a wasteful number, since it uses less digits than its factorization.

81515919888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 354094 (or 354082 counting only the distinct ones).

The product of its digits is 8294400, while the sum is 63.

The spelling of 81515919888 in words is "eighty-one billion, five hundred fifteen million, nine hundred nineteen thousand, eight hundred eighty-eight".