81273565 has 8 divisors (see below), whose sum is σ = 97638840. Its totient is φ = 64945152.

The previous prime is 81273553. The next prime is 81273581. The reversal of 81273565 is 56537218.

It can be written as a sum of positive squares in 4 ways, for example, as 10478169 + 70795396 = 3237^2 + 8414^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81273565 is a prime.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 4104 + ... + 13393.

It is an arithmetic number, because the mean of its divisors is an integer number (12204855).

Almost surely, 2^81273565 is an apocalyptic number.

It is an amenable number.

81273565 is a deficient number, since it is larger than the sum of its proper divisors (16365275).

81273565 is a wasteful number, since it uses less digits than its factorization.

81273565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18431.

The product of its digits is 50400, while the sum is 37.

The square root of 81273565 is about 9015.1852449076. The cubic root of 81273565 is about 433.1614212887.

The spelling of 81273565 in words is "eighty-one million, two hundred seventy-three thousand, five hundred sixty-five".