81228 has 24 divisors (see below), whose sum is σ = 216832. Its totient is φ = 23184.

The previous prime is 81223. The next prime is 81233. The reversal of 81228 is 82218.

It is an interprime number because it is at equal distance from previous prime (81223) and next prime (81233).

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

It is not an unprimeable number, because it can be changed into a prime (81223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 400 + ... + 567.

2⁸¹²²⁸ is an apocalyptic number.

It is an amenable number.

81228 is an abundant number, since it is smaller than the sum of its proper divisors (135604).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108416).

81228 is a wasteful number, since it uses less digits than its factorization.

81228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 981 (or 979 counting only the distinct ones).

The product of its digits is 256, while the sum is 21.

The square root of 81228 is about 285.0052631093. The cubic root of 81228 is about 43.3080457326.

Subtracting 81228 from its reverse (82218), we obtain a triangular number (990 = T₄₄).

The spelling of 81228 in words is "eighty-one thousand, two hundred twenty-eight".