81693321 has 8 divisors (see below), whose sum is σ = 109135584. Its totient is φ = 54356640.

The previous prime is 81693289. The next prime is 81693371. The reversal of 81693321 is 12339618.

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

It is not a de Polignac number, because 81693321 - 2⁵ = 81693289 is a prime.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (81693371) 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, 24571 + ... + 27696.

It is an arithmetic number, because the mean of its divisors is an integer number (13641948).

Almost surely, 2^81693321 is an apocalyptic number.

It is an amenable number.

81693321 is a deficient number, since it is larger than the sum of its proper divisors (27442263).

81693321 is a wasteful number, since it uses less digits than its factorization.

81693321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52791.

The product of its digits is 7776, while the sum is 33.

The square root of 81693321 is about 9038.4357606834. The cubic root of 81693321 is about 433.9058617060.

The spelling of 81693321 in words is "eighty-one million, six hundred ninety-three thousand, three hundred twenty-one".