279991 has 2 divisors, whose sum is σ = 279992. Its totient is φ = 279990.

The previous prime is 279977. The next prime is 280001. The reversal of 279991 is 199972.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 279991 - 2⁷ = 279863 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 279991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (279941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 139995 + 139996.

It is an arithmetic number, because the mean of its divisors is an integer number (139996).

2²⁷⁹⁹⁹¹ is an apocalyptic number.

279991 is the 306-th hex number.

279991 is a deficient number, since it is larger than the sum of its proper divisors (1).

279991 is an equidigital number, since it uses as much as digits as its factorization.

279991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10206, while the sum is 37.

The square root of 279991 is about 529.1417579439. The cubic root of 279991 is about 65.4206252535.

The spelling of 279991 in words is "two hundred seventy-nine thousand, nine hundred ninety-one".