81220 has 24 divisors (see below), whose sum is σ = 177408. Its totient is φ = 31200.

The previous prime is 81203. The next prime is 81223. The reversal of 81220 is 2218.

It is a self number, because there is not a number n which added to its sum of digits gives 81220.

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, 555 + ... + 685.

It is an arithmetic number, because the mean of its divisors is an integer number (7392).

2⁸¹²²⁰ 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 81220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (88704).

81220 is an abundant number, since it is smaller than the sum of its proper divisors (96188).

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

81220 is a wasteful number, since it uses less digits than its factorization.

81220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 169 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 81220 is about 284.9912279352. The cubic root of 81220 is about 43.3066239086.

Adding to 81220 its reverse (2218), we get a palindrome (83438).

The spelling of 81220 in words is "eighty-one thousand, two hundred twenty".