279981 has 12 divisors (see below), whose sum is σ = 435708. Its totient is φ = 172224.

The previous prime is 279977. The next prime is 279991. The reversal of 279981 is 189972.

279981 = 91² + 92² + ... + 116².

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 19881 + 260100 = 141^2 + 510^2 .

It is not a de Polignac number, because 279981 - 2² = 279977 is a prime.

It is a super-2 number, since 2×279981² = 156778720722, which contains 22 as substring.

It is an Ulam number.

279981 is a lucky number.

It is a plaindrome in base 16.

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 279981.

It is not an unprimeable number, because it can be changed into a prime (279941) 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, 1080 + ... + 1313.

It is an arithmetic number, because the mean of its divisors is an integer number (36309).

2²⁷⁹⁹⁸¹ is an apocalyptic number.

It is an amenable number.

279981 is a deficient number, since it is larger than the sum of its proper divisors (155727).

279981 is a wasteful number, since it uses less digits than its factorization.

279981 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2412 (or 2409 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 279981 is about 529.1323085959. The cubic root of 279981 is about 65.4198464022.

Subtracting from 279981 its reverse (189972), we obtain a palindrome (90009).

The spelling of 279981 in words is "two hundred seventy-nine thousand, nine hundred eighty-one".