81856471 has 8 divisors (see below), whose sum is σ = 85554144. Its totient is φ = 78170400.

The previous prime is 81856447. The next prime is 81856483. The reversal of 81856471 is 17465818.

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 81856471 - 2⁹ = 81855959 is a prime.

It is a super-3 number, since 3×81856471³ (a number of 25 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81856441) 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, 13585 + ... + 18661.

It is an arithmetic number, because the mean of its divisors is an integer number (10694268).

Almost surely, 2^81856471 is an apocalyptic number.

81856471 is a deficient number, since it is larger than the sum of its proper divisors (3697673).

81856471 is a wasteful number, since it uses less digits than its factorization.

81856471 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5801.

The product of its digits is 53760, while the sum is 40.

The square root of 81856471 is about 9047.4566039302. The cubic root of 81856471 is about 434.1945212380.

The spelling of 81856471 in words is "eighty-one million, eight hundred fifty-six thousand, four hundred seventy-one".