81237931 has 8 divisors (see below), whose sum is σ = 82218240. Its totient is φ = 80261928.

The previous prime is 81237913. The next prime is 81237973. The reversal of 81237931 is 13973218.

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 81237931 - 2⁵ = 81237899 is a prime.

It is a super-2 number, since 2×81237931² = 13199202866321522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81217931) 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 7 ways as a sum of consecutive naturals, for example, 51330 + ... + 52888.

It is an arithmetic number, because the mean of its divisors is an integer number (10277280).

Almost surely, 2^81237931 is an apocalyptic number.

81237931 is a deficient number, since it is larger than the sum of its proper divisors (980309).

81237931 is a wasteful number, since it uses less digits than its factorization.

81237931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2153.

The product of its digits is 9072, while the sum is 34.

The square root of 81237931 is about 9013.2086961304. The cubic root of 81237931 is about 433.0981061936.

The spelling of 81237931 in words is "eighty-one million, two hundred thirty-seven thousand, nine hundred thirty-one".