81608109 has 48 divisors (see below), whose sum is σ = 129676800. Its totient is φ = 45239040.

The previous prime is 81608083. The next prime is 81608113. The reversal of 81608109 is 90180618.

It is not a de Polignac number, because 81608109 - 2⁸ = 81607853 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81608109.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81608159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 409992 + ... + 410190.

It is an arithmetic number, because the mean of its divisors is an integer number (2701600).

Almost surely, 2^81608109 is an apocalyptic number.

It is an amenable number.

81608109 is a deficient number, since it is larger than the sum of its proper divisors (48068691).

81608109 is a wasteful number, since it uses less digits than its factorization.

81608109 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 290 (or 273 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 33.

The square root of 81608109 is about 9033.7206620528. The cubic root of 81608109 is about 433.7549442308.

The spelling of 81608109 in words is "eighty-one million, six hundred eight thousand, one hundred nine".