280305 has 12 divisors (see below), whose sum is σ = 485940. Its totient is φ = 149472.

The previous prime is 280303. The next prime is 280321. The reversal of 280305 is 503082.

It can be written as a sum of positive squares in 2 ways, for example, as 121104 + 159201 = 348^2 + 399^2 .

It is not a de Polignac number, because 280305 - 2¹ = 280303 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 280305.

It is not an unprimeable number, because it can be changed into a prime (280303) 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, 3070 + ... + 3159.

It is an arithmetic number, because the mean of its divisors is an integer number (40495).

2²⁸⁰³⁰⁵ is an apocalyptic number.

It is an amenable number.

280305 is a deficient number, since it is larger than the sum of its proper divisors (205635).

280305 is a wasteful number, since it uses less digits than its factorization.

280305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6240 (or 6237 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 280305 is about 529.4383816838. The cubic root of 280305 is about 65.4450717560.

Adding to 280305 its reverse (503082), we get a palindrome (783387).

It can be divided in two parts, 280 and 305, that added together give a palindrome (585).

The spelling of 280305 in words is "two hundred eighty thousand, three hundred five".