81329281 has 8 divisors (see below), whose sum is σ = 90887328. Its totient is φ = 72132000.

The previous prime is 81329263. The next prime is 81329323. The reversal of 81329281 is 18292318.

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 81329281 - 2¹³ = 81321089 is a prime.

It is a super-2 number, since 2×81329281² = 13228903895953922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81329251) 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, 89715 + ... + 90616.

It is an arithmetic number, because the mean of its divisors is an integer number (11360916).

Almost surely, 2^81329281 is an apocalyptic number.

It is an amenable number.

81329281 is a deficient number, since it is larger than the sum of its proper divisors (9558047).

81329281 is a wasteful number, since it uses less digits than its factorization.

81329281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180383.

The product of its digits is 6912, while the sum is 34.

The square root of 81329281 is about 9018.2748350225. The cubic root of 81329281 is about 433.2603813418.

The spelling of 81329281 in words is "eighty-one million, three hundred twenty-nine thousand, two hundred eighty-one".