81237971 has 4 divisors (see below), whose sum is σ = 81291000. Its totient is φ = 81184944.

The previous prime is 81237913. The next prime is 81237973. The reversal of 81237971 is 17973218.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81237971 - 2¹⁴ = 81221587 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81237973) 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 3 ways as a sum of consecutive naturals, for example, 24146 + ... + 27303.

It is an arithmetic number, because the mean of its divisors is an integer number (20322750).

Almost surely, 2^81237971 is an apocalyptic number.

81237971 is a deficient number, since it is larger than the sum of its proper divisors (53029).

81237971 is a wasteful number, since it uses less digits than its factorization.

81237971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53028.

The product of its digits is 21168, while the sum is 38.

The square root of 81237971 is about 9013.2109150957. The cubic root of 81237971 is about 433.0981772767.

It can be divided in two parts, 812 and 37971, that added together give a palindrome (38783).

The spelling of 81237971 in words is "eighty-one million, two hundred thirty-seven thousand, nine hundred seventy-one".