81465665 has 4 divisors (see below), whose sum is σ = 97758804. Its totient is φ = 65172528.

The previous prime is 81465661. The next prime is 81465667. The reversal of 81465665 is 56656418.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 42627841 + 38837824 = 6529^2 + 6232^2 .

It is a cyclic number.

It is not a de Polignac number, because 81465665 - 2² = 81465661 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81465661) 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 in 3 ways as a sum of consecutive naturals, for example, 8146562 + ... + 8146571.

It is an arithmetic number, because the mean of its divisors is an integer number (24439701).

Almost surely, 2^81465665 is an apocalyptic number.

It is an amenable number.

81465665 is a deficient number, since it is larger than the sum of its proper divisors (16293139).

81465665 is a wasteful number, since it uses less digits than its factorization.

81465665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16293138.

The product of its digits is 172800, while the sum is 41.

The square root of 81465665 is about 9025.8332025359. The cubic root of 81465665 is about 433.5024294042.

The spelling of 81465665 in words is "eighty-one million, four hundred sixty-five thousand, six hundred sixty-five".