1279889721 has 48 divisors (see below), whose sum is σ = 2092036800. Its totient is φ = 772770240.

The previous prime is 1279889713. The next prime is 1279889731.

1279889721 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 1279889721 - 2³ = 1279889713 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1279889731) 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 47 ways as a sum of consecutive naturals, for example, 1133085 + ... + 1134213.

It is an arithmetic number, because the mean of its divisors is an integer number (43584100).

Almost surely, 2^1279889721 is an apocalyptic number.

1279889721 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1279889721 is a deficient number, since it is larger than the sum of its proper divisors (812147079).

1279889721 is a wasteful number, since it uses less digits than its factorization.

1279889721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1507 (or 1490 counting only the distinct ones).

The product of its digits is 1016064, while the sum is 54.

The square root of 1279889721 is about 35775.5464109215. The cubic root of 1279889721 is about 1085.7358641528.

The spelling of 1279889721 in words is "one billion, two hundred seventy-nine million, eight hundred eighty-nine thousand, seven hundred twenty-one".