81255939912 has 384 divisors, whose sum is σ = 274799616000. Its totient is φ = 22461364800.

The previous prime is 81255939901. The next prime is 81255939931. The reversal of 81255939912 is 21993955218.

It is a happy number.

81255939912 is a `hidden beast` number, since 81 + 2 + 559 + 3 + 9 + 9 + 1 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 20668587 + ... + 20672517.

It is an arithmetic number, because the mean of its divisors is an integer number (715624000).

Almost surely, 2^81255939912 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 81255939912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137399808000).

81255939912 is an abundant number, since it is smaller than the sum of its proper divisors (193543676088).

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

81255939912 is a wasteful number, since it uses less digits than its factorization.

81255939912 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4004 (or 3974 counting only the distinct ones).

The product of its digits is 1749600, while the sum is 54.

The spelling of 81255939912 in words is "eighty-one billion, two hundred fifty-five million, nine hundred thirty-nine thousand, nine hundred twelve".