778664880543665 has 16 divisors (see below), whose sum is σ = 941059225563600. Its totient is φ = 618506331770880.

The previous prime is 778664880543659. The next prime is 778664880543679. The reversal of 778664880543665 is 566345088466877.

It can be written as a sum of positive squares in 8 ways, for example, as 131359288819264 + 647305591724401 = 11461208^2 + 25442201^2 .

It is not a de Polignac number, because 778664880543665 - 2³⁰ = 778663806801841 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 958340090 + ... + 959152259.

It is an arithmetic number, because the mean of its divisors is an integer number (58816201597725).

Almost surely, 2^{778664880543665} is an apocalyptic number.

It is an amenable number.

778664880543665 is a deficient number, since it is larger than the sum of its proper divisors (162394345019935).

778664880543665 is a wasteful number, since it uses less digits than its factorization.

778664880543665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1917492932.

The product of its (nonzero) digits is 39016857600, while the sum is 83.

The spelling of 778664880543665 in words is "seven hundred seventy-eight trillion, six hundred sixty-four billion, eight hundred eighty million, five hundred forty-three thousand, six hundred sixty-five".