778555820 has 48 divisors (see below), whose sum is σ = 1878085440. Its totient is φ = 265569024.

The previous prime is 778555777. The next prime is 778555901. The reversal of 778555820 is 28555877.

It is a super-2 number, since 2×778555820² = 1212298329711744800, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13466 + ... + 41694.

It is an arithmetic number, because the mean of its divisors is an integer number (39126780).

Almost surely, 2^778555820 is an apocalyptic number.

778555820 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 778555820, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (939042720).

778555820 is an abundant number, since it is smaller than the sum of its proper divisors (1099529620).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

778555820 is a wasteful number, since it uses less digits than its factorization.

778555820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28442 (or 28440 counting only the distinct ones).

The product of its (nonzero) digits is 784000, while the sum is 47.

The square root of 778555820 is about 27902.6131392742. The cubic root of 778555820 is about 919.9479412887.

The spelling of 778555820 in words is "seven hundred seventy-eight million, five hundred fifty-five thousand, eight hundred twenty".