280666 has 4 divisors (see below), whose sum is σ = 421002. Its totient is φ = 140332.

The previous prime is 280639. The next prime is 280673. The reversal of 280666 is 666082.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 666082 = 2 ⋅333041.

It can be written as a sum of positive squares in only one way, i.e., 275625 + 5041 = 525^2 + 71^2 .

280666 is a modest number, since divided by 666 gives 280 as remainder.

It is an unprimeable number.

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, 70165 + ... + 70168.

2²⁸⁰⁶⁶⁶ is an apocalyptic number.

280666 is a deficient number, since it is larger than the sum of its proper divisors (140336).

280666 is a wasteful number, since it uses less digits than its factorization.

280666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140335.

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 280666 is about 529.7791992897. The cubic root of 280666 is about 65.4731548985.

It can be divided in two parts, 280 and 666, that added together give a triangular number (946 = T₄₃).

The spelling of 280666 in words is "two hundred eighty thousand, six hundred sixty-six".