81003216 has 60 divisors (see below), whose sum is σ = 239640416. Its totient is φ = 23096640.

The previous prime is 81003187. The next prime is 81003229. The reversal of 81003216 is 61230018.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 81003192 and 81003201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 164731 + ... + 165221.

Almost surely, 2^81003216 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 81003216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (119820208).

81003216 is an abundant number, since it is smaller than the sum of its proper divisors (158637200).

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

81003216 is an equidigital number, since it uses as much as digits as its factorization.

81003216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000 (or 503 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 81003216 is about 9000.1786648933. The cubic root of 81003216 is about 432.6805972814.

Multiplying 81003216 by its sum of digits (21), we get a square (1701067536 = 41244²).

81003216 divided by its sum of digits (21) gives a square (3857296 = 1964²).

The spelling of 81003216 in words is "eighty-one million, three thousand, two hundred sixteen".