81717505585 has 8 divisors (see below), whose sum is σ = 98071254720.
Its totient is φ = 65367172464.
The previous prime is 81717505559. The next prime is 81717505589. The reversal of 81717505585 is 58550571718.
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 81717505585 - 29 = 81717505073 is a prime.
It is not an unprimeable number, because it can be changed into a prime (81717505589) by changing a digit.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 801075 + ... + 897304.
It is an arithmetic number, because the mean of its divisors is an integer number (12258906840).
Almost surely, 281717505585 is an apocalyptic number.
It is an amenable number.
81717505585 is a deficient number, since it is larger than the sum of its proper divisors (16353749135).
81717505585 is a wasteful number, since it uses less digits than its factorization.
81717505585 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1708007.
The product of its (nonzero) digits is 1960000, while the sum is 52.
The spelling of 81717505585 in words is "eighty-one billion, seven hundred seventeen million, five hundred five thousand, five hundred eighty-five".