280820 has 24 divisors (see below), whose sum is σ = 621600. Its totient is φ = 106272.

The previous prime is 280817. The next prime is 280837. The reversal of 280820 is 28082.

280820 = T₅ + T₆ + ... + T₁₁₈.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a junction number, because it is equal to n+sod(n) for n = 280792 and 280801.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11 + ... + 749.

It is an arithmetic number, because the mean of its divisors is an integer number (25900).

2²⁸⁰⁸²⁰ is an apocalyptic number.

280820 is a gapful number since it is divisible by the number (20) 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 280820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (310800).

280820 is an abundant number, since it is smaller than the sum of its proper divisors (340780).

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

280820 is a wasteful number, since it uses less digits than its factorization.

280820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 767 (or 765 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 280820 is about 529.9245229276. The cubic root of 280820 is about 65.4851276375.

280820 divided by its sum of digits (20) gives a palindrome (14041).

The spelling of 280820 in words is "two hundred eighty thousand, eight hundred twenty".