1279840005 has 18 divisors (see below), whose sum is σ = 2218805394. Its totient is φ = 682453344.

The previous prime is 1279839989. The next prime is 1279840007. The reversal of 1279840005 is 5000489721.

It can be written as a sum of positive squares in 3 ways, for example, as 965593476 + 314246529 = 31074^2 + 17727^2 .

It is not a de Polignac number, because 1279840005 - 2⁴ = 1279839989 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1279840007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 237319 + ... + 242651.

Almost surely, 2^1279840005 is an apocalyptic number.

1279840005 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1279840005 is a deficient number, since it is larger than the sum of its proper divisors (938965389).

1279840005 is an frugal number, since it uses more digits than its factorization.

1279840005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10677 (or 5341 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 36.

The square root of 1279840005 is about 35774.8515720191. The cubic root of 1279840005 is about 1085.7218058731.

The spelling of 1279840005 in words is "one billion, two hundred seventy-nine million, eight hundred forty thousand, five".