279991891 has 4 divisors (see below), whose sum is σ = 284581984. Its totient is φ = 275401800.

The previous prime is 279991849. The next prime is 279991927. The reversal of 279991891 is 198199972.

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

It is a cyclic number.

It is not a de Polignac number, because 279991891 - 2¹⁵ = 279959123 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (279992891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2294955 + ... + 2295076.

It is an arithmetic number, because the mean of its divisors is an integer number (71145496).

Almost surely, 2^279991891 is an apocalyptic number.

279991891 is a deficient number, since it is larger than the sum of its proper divisors (4590093).

279991891 is an equidigital number, since it uses as much as digits as its factorization.

279991891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4590092.

The product of its digits is 734832, while the sum is 55.

The square root of 279991891 is about 16732.9582262073. The cubic root of 279991891 is about 654.2069464823.

It can be divided in two parts, 27999 and 1891, that added together give a triangular number (29890 = T₂₄₄).

The spelling of 279991891 in words is "two hundred seventy-nine million, nine hundred ninety-one thousand, eight hundred ninety-one".