1279779721 has 8 divisors (see below), whose sum is σ = 1397673504. Its totient is φ = 1162144320.

The previous prime is 1279779671. The next prime is 1279779733.

It is a happy number.

1279779721 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1279779721 - 2²⁷ = 1145561993 is a prime.

It is a super-2 number, since 2×1279779721² = 3275672268565675682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1279773721) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 54160 + ... + 74113.

It is an arithmetic number, because the mean of its divisors is an integer number (174709188).

Almost surely, 2^1279779721 is an apocalyptic number.

1279779721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1279779721 is a deficient number, since it is larger than the sum of its proper divisors (117893783).

1279779721 is a wasteful number, since it uses less digits than its factorization.

1279779721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 129191.

The product of its digits is 777924, while the sum is 52.

The square root of 1279779721 is about 35774.0090149259. The cubic root of 1279779721 is about 1085.7047587732.

The spelling of 1279779721 in words is "one billion, two hundred seventy-nine million, seven hundred seventy-nine thousand, seven hundred twenty-one".