81583616 has 40 divisors (see below), whose sum is σ = 165153120. Its totient is φ = 40255488.

The previous prime is 81583597. The next prime is 81583643. The reversal of 81583616 is 61638518.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81583616.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 39440 + ... + 41456.

It is an arithmetic number, because the mean of its divisors is an integer number (4128828).

Almost surely, 2^81583616 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 81583616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (82576560).

81583616 is an abundant number, since it is smaller than the sum of its proper divisors (83569504).

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

81583616 is an equidigital number, since it uses as much as digits as its factorization.

81583616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2114 (or 2098 counting only the distinct ones).

The product of its digits is 34560, while the sum is 38.

The square root of 81583616 is about 9032.3649173403. The cubic root of 81583616 is about 433.7115456722.

The spelling of 81583616 in words is "eighty-one million, five hundred eighty-three thousand, six hundred sixteen".