81943871 has 16 divisors (see below), whose sum is σ = 88482240. Its totient is φ = 75694080.

The previous prime is 81943867. The next prime is 81943877. The reversal of 81943871 is 17834918.

It is a cyclic number.

It is not a de Polignac number, because 81943871 - 2² = 81943867 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (41).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81943877) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 106175 + ... + 106943.

It is an arithmetic number, because the mean of its divisors is an integer number (5530140).

Almost surely, 2^81943871 is an apocalyptic number.

81943871 is a deficient number, since it is larger than the sum of its proper divisors (6538369).

81943871 is a wasteful number, since it uses less digits than its factorization.

81943871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 946.

The product of its digits is 48384, while the sum is 41.

The square root of 81943871 is about 9052.2854020407. The cubic root of 81943871 is about 434.3489993650.

The spelling of 81943871 in words is "eighty-one million, nine hundred forty-three thousand, eight hundred seventy-one".