81221612 has 12 divisors (see below), whose sum is σ = 146723136. Its totient is φ = 39300720.

The previous prime is 81221603. The next prime is 81221617. The reversal of 81221612 is 21612218.

It is not an unprimeable number, because it can be changed into a prime (81221617) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 327383 + ... + 327630.

It is an arithmetic number, because the mean of its divisors is an integer number (12226928).

Almost surely, 2^81221612 is an apocalyptic number.

It is an amenable number.

81221612 is a deficient number, since it is larger than the sum of its proper divisors (65501524).

81221612 is a wasteful number, since it uses less digits than its factorization.

81221612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 655048 (or 655046 counting only the distinct ones).

The product of its digits is 384, while the sum is 23.

The square root of 81221612 is about 9012.3033681740. The cubic root of 81221612 is about 433.0691041367.

The spelling of 81221612 in words is "eighty-one million, two hundred twenty-one thousand, six hundred twelve".