81280 has 32 divisors (see below), whose sum is σ = 195840. Its totient is φ = 32256.

The previous prime is 81239. The next prime is 81281. The reversal of 81280 is 8218.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81281) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 577 + ... + 703.

It is an arithmetic number, because the mean of its divisors is an integer number (6120).

2⁸¹²⁸⁰ is an apocalyptic number.

81280 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97920).

81280 is an abundant number, since it is smaller than the sum of its proper divisors (114560).

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

81280 is a wasteful number, since it uses less digits than its factorization.

81280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 81280 is about 285.0964748993. The cubic root of 81280 is about 43.3172853133.

Adding to 81280 its reverse (8218), we get a palindrome (89498).

It can be divided in two parts, 81 and 280, that added together give a square (361 = 19²).

The spelling of 81280 in words is "eighty-one thousand, two hundred eighty".