81445931 has 8 divisors (see below), whose sum is σ = 93135840. Its totient is φ = 69769728.

The previous prime is 81445909. The next prime is 81445957. The reversal of 81445931 is 13954418.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81445931 - 2¹⁸ = 81183787 is a prime.

It is a super-4 number, since 4×81445931⁴ (a number of 33 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 81445891 and 81445900.

It is not an unprimeable number, because it can be changed into a prime (81445981) 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 7 ways as a sum of consecutive naturals, for example, 20105 + ... + 23813.

It is an arithmetic number, because the mean of its divisors is an integer number (11641980).

Almost surely, 2^81445931 is an apocalyptic number.

81445931 is a deficient number, since it is larger than the sum of its proper divisors (11689909).

81445931 is a wasteful number, since it uses less digits than its factorization.

81445931 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6853.

The product of its digits is 17280, while the sum is 35.

The square root of 81445931 is about 9024.7399408515. The cubic root of 81445931 is about 433.4674231318.

The spelling of 81445931 in words is "eighty-one million, four hundred forty-five thousand, nine hundred thirty-one".