81189321 has 4 divisors (see below), whose sum is σ = 108252432. Its totient is φ = 54126212.

The previous prime is 81189319. The next prime is 81189343. The reversal of 81189321 is 12398118.

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 81189321 - 2¹ = 81189319 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81189301) 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, 13531551 + ... + 13531556.

It is an arithmetic number, because the mean of its divisors is an integer number (27063108).

Almost surely, 2^81189321 is an apocalyptic number.

It is an amenable number.

81189321 is a deficient number, since it is larger than the sum of its proper divisors (27063111).

81189321 is a wasteful number, since it uses less digits than its factorization.

81189321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27063110.

The product of its digits is 3456, while the sum is 33.

The square root of 81189321 is about 9010.5116946819. The cubic root of 81189321 is about 433.0117052592.

The spelling of 81189321 in words is "eighty-one million, one hundred eighty-nine thousand, three hundred twenty-one".