81965648 has 10 divisors (see below), whose sum is σ = 158808474. Its totient is φ = 40982816.

The previous prime is 81965647. The next prime is 81965699. The reversal of 81965648 is 84656918.

It can be written as a sum of positive squares in only one way, i.e., 77933584 + 4032064 = 8828^2 + 2008^2 .

It is a super-3 number, since 3×81965648³ (a number of 25 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81965647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2561411 + ... + 2561442.

Almost surely, 2^81965648 is an apocalyptic number.

It is an amenable number.

81965648 is a deficient number, since it is larger than the sum of its proper divisors (76842826).

81965648 is a wasteful number, since it uses less digits than its factorization.

81965648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5122861 (or 5122855 counting only the distinct ones).

The product of its digits is 414720, while the sum is 47.

The square root of 81965648 is about 9053.4881675518. The cubic root of 81965648 is about 434.3874727747.

The spelling of 81965648 in words is "eighty-one million, nine hundred sixty-five thousand, six hundred forty-eight".