81619616 has 24 divisors (see below), whose sum is σ = 173050164. Its totient is φ = 37670400.

The previous prime is 81619613. The next prime is 81619723. The reversal of 81619616 is 61691618.

It can be written as a sum of positive squares in 2 ways, for example, as 81072016 + 547600 = 9004^2 + 740^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 81619616.

It is not an unprimeable number, because it can be changed into a prime (81619613) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97685 + ... + 98516.

Almost surely, 2^81619616 is an apocalyptic number.

It is an amenable number.

81619616 is an abundant number, since it is smaller than the sum of its proper divisors (91430548).

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

81619616 is a wasteful number, since it uses less digits than its factorization.

81619616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196224 (or 196216 counting only the distinct ones).

The product of its digits is 15552, while the sum is 38.

The square root of 81619616 is about 9034.3575311142. The cubic root of 81619616 is about 433.7753302097.

The spelling of 81619616 in words is "eighty-one million, six hundred nineteen thousand, six hundred sixteen".