821280 has 96 divisors (see below), whose sum is σ = 2721600. Its totient is φ = 207872.

The previous prime is 821263. The next prime is 821281. The reversal of 821280 is 82128.

It is a tau number, because it is divible by the number of its divisors (96).

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (821281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13891 + ... + 13949.

It is an arithmetic number, because the mean of its divisors is an integer number (28350).

2⁸²¹²⁸⁰ is an apocalyptic number.

821280 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 821280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1360800).

821280 is an abundant number, since it is smaller than the sum of its proper divisors (1900320).

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

821280 is a wasteful number, since it uses less digits than its factorization.

821280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 98 counting only the distinct ones).

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

The square root of 821280 is about 906.2449999862. The cubic root of 821280 is about 93.6476928397.

The spelling of 821280 in words is "eight hundred twenty-one thousand, two hundred eighty".