1216798857 has 12 divisors (see below), whose sum is σ = 1790761284. Its totient is φ = 795893280.

The previous prime is 1216798853. The next prime is 1216798873. The reversal of 1216798857 is 7588976121.

It can be written as a sum of positive squares in 2 ways, for example, as 568536336 + 648262521 = 23844^2 + 25461^2 .

It is not a de Polignac number, because 1216798857 - 2² = 1216798853 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1216798853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1274994 + ... + 1275947.

It is an arithmetic number, because the mean of its divisors is an integer number (149230107).

Almost surely, 2^1216798857 is an apocalyptic number.

It is an amenable number.

1216798857 is a deficient number, since it is larger than the sum of its proper divisors (573962427).

1216798857 is a wasteful number, since it uses less digits than its factorization.

1216798857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2551000 (or 2550997 counting only the distinct ones).

The product of its digits is 1693440, while the sum is 54.

The square root of 1216798857 is about 34882.6440654948. The cubic root of 1216798857 is about 1067.5943442149.

The spelling of 1216798857 in words is "one billion, two hundred sixteen million, seven hundred ninety-eight thousand, eight hundred fifty-seven".