280809 has 12 divisors (see below), whose sum is σ = 416052. Its totient is φ = 182400.

The previous prime is 280771. The next prime is 280811. The reversal of 280809 is 908082.

It can be written as a sum of positive squares in 2 ways, for example, as 5184 + 275625 = 72^2 + 525^2 .

It is not a de Polignac number, because 280809 - 2⁷ = 280681 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 280809.

It is not an unprimeable number, because it can be changed into a prime (280859) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12 + ... + 749.

It is an arithmetic number, because the mean of its divisors is an integer number (34671).

2²⁸⁰⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

280809 is a deficient number, since it is larger than the sum of its proper divisors (135243).

280809 is a wasteful number, since it uses less digits than its factorization.

280809 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 808 (or 805 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 27.

The square root of 280809 is about 529.9141439894. The cubic root of 280809 is about 65.4842725870.

Adding to 280809 its product of nonzero digits (1152), we get a square (281961 = 531²).

It can be divided in two parts, 280 and 809, that added together give a square (1089 = 33²).

The spelling of 280809 in words is "two hundred eighty thousand, eight hundred nine".