81319960512 has 168 divisors, whose sum is σ = 266674591872. Its totient is φ = 23209228800.

The previous prime is 81319960459. The next prime is 81319960529. The reversal of 81319960512 is 21506991318.

81319960512 is a `hidden beast` number, since 8 + 1 + 31 + 9 + 9 + 605 + 1 + 2 = 666.

It is a tau number, because it is divible by the number of its divisors (168).

It is a super-2 number, since 2×81319960512² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3904687 + ... + 3925457.

Almost surely, 2^81319960512 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 81319960512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (133337295936).

81319960512 is an abundant number, since it is smaller than the sum of its proper divisors (185354631360).

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

81319960512 is a wasteful number, since it uses less digits than its factorization.

81319960512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21767 (or 21754 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The spelling of 81319960512 in words is "eighty-one billion, three hundred nineteen million, nine hundred sixty thousand, five hundred twelve".