81221318 has 8 divisors (see below), whose sum is σ = 121976712. Its totient is φ = 40562416.

The previous prime is 81221299. The next prime is 81221321. The reversal of 81221318 is 81312218.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21980 + ... + 25407.

It is an arithmetic number, because the mean of its divisors is an integer number (15247089).

Almost surely, 2^81221318 is an apocalyptic number.

81221318 is a deficient number, since it is larger than the sum of its proper divisors (40755394).

81221318 is a wasteful number, since it uses less digits than its factorization.

81221318 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48246.

The product of its digits is 768, while the sum is 26.

The square root of 81221318 is about 9012.2870571237. The cubic root of 81221318 is about 433.0685816055.

The spelling of 81221318 in words is "eighty-one million, two hundred twenty-one thousand, three hundred eighteen".