81409165 has 8 divisors (see below), whose sum is σ = 97741080. Its totient is φ = 65093952.

The previous prime is 81409117. The next prime is 81409187. The reversal of 81409165 is 56190418.

It can be written as a sum of positive squares in 4 ways, for example, as 9278116 + 72131049 = 3046^2 + 8493^2 .

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

It is a cyclic number.

It is not a de Polignac number, because 81409165 - 2¹⁹ = 80884877 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81409165.

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, 12927 + ... + 18163.

It is an arithmetic number, because the mean of its divisors is an integer number (12217635).

Almost surely, 2^81409165 is an apocalyptic number.

It is an amenable number.

81409165 is a deficient number, since it is larger than the sum of its proper divisors (16331915).

81409165 is a wasteful number, since it uses less digits than its factorization.

81409165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8351.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 81409165 is about 9022.7027547182. The cubic root of 81409165 is about 433.4021885983.

The spelling of 81409165 in words is "eighty-one million, four hundred nine thousand, one hundred sixty-five".