81330321 has 8 divisors (see below), whose sum is σ = 108501120. Its totient is φ = 54189872.

The previous prime is 81330313. The next prime is 81330343. The reversal of 81330321 is 12303318.

It is a happy number.

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 81330321 - 2³ = 81330313 is a prime.

It is a super-2 number, since 2×81330321² = 13229242227926082, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81330311) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 345 + ... + 12758.

It is an arithmetic number, because the mean of its divisors is an integer number (13562640).

Almost surely, 2^81330321 is an apocalyptic number.

It is an amenable number.

81330321 is a deficient number, since it is larger than the sum of its proper divisors (27170799).

81330321 is a wasteful number, since it uses less digits than its factorization.

81330321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15175.

The product of its (nonzero) digits is 432, while the sum is 21.

The square root of 81330321 is about 9018.3324955338. The cubic root of 81330321 is about 433.2622281095.

Adding to 81330321 its reverse (12303318), we get a palindrome (93633639).

The spelling of 81330321 in words is "eighty-one million, three hundred thirty thousand, three hundred twenty-one".