81289321 has 4 divisors (see below), whose sum is σ = 81358992. Its totient is φ = 81219652.

The previous prime is 81289309. The next prime is 81289339. The reversal of 81289321 is 12398218.

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.

It is a cyclic number.

It is not a de Polignac number, because 81289321 - 2¹¹ = 81287273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81289301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33055 + ... + 35428.

It is an arithmetic number, because the mean of its divisors is an integer number (20339748).

Almost surely, 2^81289321 is an apocalyptic number.

It is an amenable number.

81289321 is a deficient number, since it is larger than the sum of its proper divisors (69671).

81289321 is a wasteful number, since it uses less digits than its factorization.

81289321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69670.

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

The square root of 81289321 is about 9016.0590614747. The cubic root of 81289321 is about 433.1894109159.

The spelling of 81289321 in words is "eighty-one million, two hundred eighty-nine thousand, three hundred twenty-one".