778223981 has 2 divisors, whose sum is σ = 778223982. Its totient is φ = 778223980.

The previous prime is 778223891. The next prime is 778223989. The reversal of 778223981 is 189322877.

778223981 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with previous prime (778223891) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 444577225 + 333646756 = 21085^2 + 18266^2 .

It is an emirp because it is prime and its reverse (189322877) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 778223981 - 2¹⁴ = 778207597 is a prime.

It is a super-2 number, since 2×778223981² = 1211265129206976722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (778223989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389111990 + 389111991.

It is an arithmetic number, because the mean of its divisors is an integer number (389111991).

Almost surely, 2^778223981 is an apocalyptic number.

It is an amenable number.

778223981 is a deficient number, since it is larger than the sum of its proper divisors (1).

778223981 is an equidigital number, since it uses as much as digits as its factorization.

778223981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 338688, while the sum is 47.

The square root of 778223981 is about 27896.6661269765. Note that the first 3 decimals coincide. The cubic root of 778223981 is about 919.8172214871.

The spelling of 778223981 in words is "seven hundred seventy-eight million, two hundred twenty-three thousand, nine hundred eighty-one".