81216212 has 48 divisors (see below), whose sum is σ = 177894528. Its totient is φ = 31518720.

The previous prime is 81216209. The next prime is 81216251. The reversal of 81216212 is 21261218.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 140468 + ... + 141044.

It is an arithmetic number, because the mean of its divisors is an integer number (3706136).

Almost surely, 2^81216212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81216212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88947264).

81216212 is an abundant number, since it is smaller than the sum of its proper divisors (96678316).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81216212 is a wasteful number, since it uses less digits than its factorization.

81216212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1056 (or 1054 counting only the distinct ones).

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

The square root of 81216212 is about 9012.0037727467. The cubic root of 81216212 is about 433.0595064244.

The spelling of 81216212 in words is "eighty-one million, two hundred sixteen thousand, two hundred twelve".