280840 has 64 divisors (see below), whose sum is σ = 777600. Its totient is φ = 89088.

The previous prime is 280837. The next prime is 280843. The reversal of 280840 is 48082.

280840 = T₁ + T₂ + ... + T₁₁₈.

280840 is a nontrivial binomial coefficient, being equal to C(120, 3).

It is an interprime number because it is at equal distance from previous prime (280837) and next prime (280843).

It is a super-2 number, since 2×280840² = 157742211200, which contains 22 as substring.

280840 is a modest number, since divided by 840 gives 280 as remainder.

It is not an unprimeable number, because it can be changed into a prime (280843) by changing a digit.

It is the 118-th tetrahedral number.

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, 4731 + ... + 4789.

It is an arithmetic number, because the mean of its divisors is an integer number (12150).

2²⁸⁰⁸⁴⁰ is an apocalyptic number.

280840 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 280840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (388800).

280840 is an abundant number, since it is smaller than the sum of its proper divisors (496760).

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

280840 is a wasteful number, since it uses less digits than its factorization.

280840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 94 (or 90 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 22.

The square root of 280840 is about 529.9433932035. The cubic root of 280840 is about 65.4866822175.

The spelling of 280840 in words is "two hundred eighty thousand, eight hundred forty".