81317471 has 4 divisors (see below), whose sum is σ = 81344592.
Its totient is φ = 81290352.
The previous prime is 81317461. The next prime is 81317491. The reversal of 81317471 is 17471318.
It is a happy number.
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is not a de Polignac number, because 81317471 - 26 = 81317407 is a prime.
It is a super-3 number, since 3×813174713 (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (81317441) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8411 + ... + 15276.
It is an arithmetic number, because the mean of its divisors is an integer number (20336148).
Almost surely, 281317471 is an apocalyptic number.
81317471 is a deficient number, since it is larger than the sum of its proper divisors (27121).
81317471 is a wasteful number, since it uses less digits than its factorization.
81317471 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 27120.
The product of its digits is 4704, while the sum is 32.
The square root of 81317471 is about 9017.6200296974.
The cubic root of 81317471 is about 433.2394087690.
Adding to 81317471 its reverse (17471318), we get a palindrome (98788789).
The spelling of 81317471 in words is "eighty-one million, three hundred seventeen thousand, four hundred seventy-one".