81965568 has 160 divisors (see below), whose sum is σ = 239823936. Its totient is φ = 24772608.

The previous prime is 81965561. The next prime is 81965579. The reversal of 81965568 is 86556918.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (81965561) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1122780 + ... + 1122852.

Almost surely, 2^81965568 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 81965568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119911968).

81965568 is an abundant number, since it is smaller than the sum of its proper divisors (157858368).

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

81965568 is a wasteful number, since it uses less digits than its factorization.

81965568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 154 (or 138 counting only the distinct ones).

The product of its digits is 518400, while the sum is 48.

The square root of 81965568 is about 9053.4837493641. The cubic root of 81965568 is about 434.3873314512.

The spelling of 81965568 in words is "eighty-one million, nine hundred sixty-five thousand, five hundred sixty-eight".