778936639891 has 2 divisors, whose sum is σ = 778936639892. Its totient is φ = 778936639890.

The previous prime is 778936639861. The next prime is 778936639909. The reversal of 778936639891 is 198936639877.

It is a strong prime.

It is an emirp because it is prime and its reverse (198936639877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 778936639891 - 2¹³ = 778936631699 is a prime.

It is not a weakly prime, because it can be changed into another prime (778936639841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389468319945 + 389468319946.

It is an arithmetic number, because the mean of its divisors is an integer number (389468319946).

Almost surely, 2^778936639891 is an apocalyptic number.

778936639891 is a deficient number, since it is larger than the sum of its proper divisors (1).

778936639891 is an equidigital number, since it uses as much as digits as its factorization.

778936639891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 740710656, while the sum is 76.

The spelling of 778936639891 in words is "seven hundred seventy-eight billion, nine hundred thirty-six million, six hundred thirty-nine thousand, eight hundred ninety-one".