280138 has 4 divisors (see below), whose sum is σ = 420210. Its totient is φ = 140068.

The previous prime is 280129. The next prime is 280139. The reversal of 280138 is 831082.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 208849 + 71289 = 457^2 + 267^2 .

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (280139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 70033 + ... + 70036.

2²⁸⁰¹³⁸ is an apocalyptic number.

280138 is a deficient number, since it is larger than the sum of its proper divisors (140072).

280138 is a wasteful number, since it uses less digits than its factorization.

280138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140071.

The product of its (nonzero) digits is 384, while the sum is 22.

The square root of 280138 is about 529.2806438932. The cubic root of 280138 is about 65.4320722279.

The spelling of 280138 in words is "two hundred eighty thousand, one hundred thirty-eight".