81999344 has 60 divisors (see below), whose sum is σ = 189394128. Its totient is φ = 34272000.

The previous prime is 81999329. The next prime is 81999353. The reversal of 81999344 is 44399918.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30869 + ... + 33419.

Almost surely, 2^81999344 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 81999344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94697064).

81999344 is an abundant number, since it is smaller than the sum of its proper divisors (107394784).

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

81999344 is a wasteful number, since it uses less digits than its factorization.

81999344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2614 (or 2601 counting only the distinct ones).

The product of its digits is 279936, while the sum is 47.

The square root of 81999344 is about 9055.3489165244. The cubic root of 81999344 is about 434.4469900454.

The spelling of 81999344 in words is "eighty-one million, nine hundred ninety-nine thousand, three hundred forty-four".