778319649 has 24 divisors (see below), whose sum is σ = 1142024832. Its totient is φ = 510701760.

The previous prime is 778319611. The next prime is 778319677. The reversal of 778319649 is 946913877.

It is a happy number.

It is not a de Polignac number, because 778319649 - 2¹⁷ = 778188577 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 778319595 and 778319604.

It is not an unprimeable number, because it can be changed into a prime (778319749) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 424164 + ... + 425994.

It is an arithmetic number, because the mean of its divisors is an integer number (47584368).

Almost surely, 2^778319649 is an apocalyptic number.

It is an amenable number.

778319649 is a deficient number, since it is larger than the sum of its proper divisors (363705183).

778319649 is a wasteful number, since it uses less digits than its factorization.

778319649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2557 (or 2554 counting only the distinct ones).

The product of its digits is 2286144, while the sum is 54.

The square root of 778319649 is about 27898.3807594634. The cubic root of 778319649 is about 919.8549113512.

The spelling of 778319649 in words is "seven hundred seventy-eight million, three hundred nineteen thousand, six hundred forty-nine".