81329 has 4 divisors (see below), whose sum is σ = 81984. Its totient is φ = 80676.

The previous prime is 81307. The next prime is 81331. The reversal of 81329 is 92318.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81329 is a prime.

It is a super-2 number, since 2×81329² = 13228812482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81349) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 77 + ... + 410.

It is an arithmetic number, because the mean of its divisors is an integer number (20496).

2⁸¹³²⁹ is an apocalyptic number.

It is an amenable number.

81329 is a deficient number, since it is larger than the sum of its proper divisors (655).

81329 is a wasteful number, since it uses less digits than its factorization.

81329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654.

The product of its digits is 432, while the sum is 23.

The square root of 81329 is about 285.1823977738. The cubic root of 81329 is about 43.3259882357.

The spelling of 81329 in words is "eighty-one thousand, three hundred twenty-nine".