81583971 has 24 divisors (see below), whose sum is σ = 130627584. Its totient is φ = 45113040.

The previous prime is 81583949. The next prime is 81583987. The reversal of 81583971 is 17938518.

It is not a de Polignac number, because 81583971 - 2¹⁰ = 81582947 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81583991) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 4395 + ... + 13508.

It is an arithmetic number, because the mean of its divisors is an integer number (5442816).

Almost surely, 2^81583971 is an apocalyptic number.

81583971 is a deficient number, since it is larger than the sum of its proper divisors (49043613).

81583971 is a wasteful number, since it uses less digits than its factorization.

81583971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17951 (or 17944 counting only the distinct ones).

The product of its digits is 60480, while the sum is 42.

The square root of 81583971 is about 9032.3845688722. The cubic root of 81583971 is about 433.7121747502.

The spelling of 81583971 in words is "eighty-one million, five hundred eighty-three thousand, nine hundred seventy-one".