81775508509 has 8 divisors (see below), whose sum is σ = 85155592320. Its totient is φ = 78432774000.

The previous prime is 81775508497. The next prime is 81775508543. The reversal of 81775508509 is 90580557718.

It is a happy number.

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 81775508509 - 2²³ = 81767119901 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81775508509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81775508599) 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 7 ways as a sum of consecutive naturals, for example, 9332857 + ... + 9341614.

It is an arithmetic number, because the mean of its divisors is an integer number (10644449040).

Almost surely, 2^81775508509 is an apocalyptic number.

It is an amenable number.

81775508509 is a deficient number, since it is larger than the sum of its proper divisors (3380083811).

81775508509 is a wasteful number, since it uses less digits than its factorization.

81775508509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18674651.

The product of its (nonzero) digits is 3528000, while the sum is 55.

The spelling of 81775508509 in words is "eighty-one billion, seven hundred seventy-five million, five hundred eight thousand, five hundred nine".