81317470 has 32 divisors (see below), whose sum is σ = 159187392.
Its totient is φ = 29728512.
The previous prime is 81317461. The next prime is 81317491. The reversal of 81317470 is 7471318.
It is a super-2 number, since 2×813174702 = 13225061854401800, which contains 22 as substring.
It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.
It is a congruent number.
It is an unprimeable number.
It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10354 + ... + 16426.
It is an arithmetic number, because the mean of its divisors is an integer number (4974606).
Almost surely, 281317470 is an apocalyptic number.
81317470 is a deficient number, since it is larger than the sum of its proper divisors (77869922).
81317470 is a wasteful number, since it uses less digits than its factorization.
81317470 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 6196.
The product of its (nonzero) digits is 4704, while the sum is 31.
The square root of 81317470 is about 9017.6199742504.
The cubic root of 81317470 is about 433.2394069931.
Adding to 81317470 its reverse (7471318), we get a palindrome (88788788).
The spelling of 81317470 in words is "eighty-one million, three hundred seventeen thousand, four hundred seventy".