81289216 has 28 divisors (see below), whose sum is σ = 162584892. Its totient is φ = 40640512.

The previous prime is 81289181. The next prime is 81289231. The reversal of 81289216 is 61298218.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3231 + ... + 13153.

Almost surely, 2^81289216 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 81289216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81292446).

81289216 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81289216 is an frugal number, since it uses more digits than its factorization.

81289216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9949 (or 9925 counting only the distinct ones).

The product of its digits is 13824, while the sum is 37.

The square root of 81289216 is about 9016.0532385296. The cubic root of 81289216 is about 433.1892244014.

The spelling of 81289216 in words is "eighty-one million, two hundred eighty-nine thousand, two hundred sixteen".