81399283992 has 480 divisors, whose sum is σ = 272911589280. Its totient is φ = 22535884800.

The previous prime is 81399283919. The next prime is 81399284011. The reversal of 81399283992 is 29938299318.

81399283992 is a `hidden beast` number, since 81 + 399 + 2 + 83 + 9 + 92 = 666.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 42818242 + ... + 42820142.

It is an arithmetic number, because the mean of its divisors is an integer number (568565811).

Almost surely, 2^81399283992 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 81399283992, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136455794640).

81399283992 is an abundant number, since it is smaller than the sum of its proper divisors (191512305288).

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

81399283992 is a wasteful number, since it uses less digits than its factorization.

81399283992 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1985 (or 1959 counting only the distinct ones).

The product of its digits is 15116544, while the sum is 63.

The spelling of 81399283992 in words is "eighty-one billion, three hundred ninety-nine million, two hundred eighty-three thousand, nine hundred ninety-two".