81965768 has 8 divisors (see below), whose sum is σ = 153685830. Its totient is φ = 40982880.

The previous prime is 81965759. The next prime is 81965777. The reversal of 81965768 is 86756918.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81965759) and next prime (81965777).

It can be written as a sum of positive squares in only one way, i.e., 70930084 + 11035684 = 8422^2 + 3322^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5122853 + ... + 5122868.

Almost surely, 2^81965768 is an apocalyptic number.

It is an amenable number.

81965768 is a deficient number, since it is larger than the sum of its proper divisors (71720062).

81965768 is a wasteful number, since it uses less digits than its factorization.

81965768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10245727 (or 10245723 counting only the distinct ones).

The product of its digits is 725760, while the sum is 50.

The square root of 81965768 is about 9053.4947948292. The cubic root of 81965768 is about 434.3876847597.

The spelling of 81965768 in words is "eighty-one million, nine hundred sixty-five thousand, seven hundred sixty-eight".