81289871 has 16 divisors (see below), whose sum is σ = 91022400. Its totient is φ = 72081408.

The previous prime is 81289867. The next prime is 81289877. The reversal of 81289871 is 17898218.

It is a cyclic number.

It is not a de Polignac number, because 81289871 - 2² = 81289867 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81289877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 96470 + ... + 97308.

It is an arithmetic number, because the mean of its divisors is an integer number (5688900).

Almost surely, 2^81289871 is an apocalyptic number.

81289871 is a deficient number, since it is larger than the sum of its proper divisors (9732529).

81289871 is a wasteful number, since it uses less digits than its factorization.

81289871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1138.

The product of its digits is 64512, while the sum is 44.

The square root of 81289871 is about 9016.0895625543. The cubic root of 81289871 is about 433.1903878939.

The spelling of 81289871 in words is "eighty-one million, two hundred eighty-nine thousand, eight hundred seventy-one".