778220640 has 144 divisors (see below), whose sum is σ = 2771260128. Its totient is φ = 198494208.

The previous prime is 778220609. The next prime is 778220657. The reversal of 778220640 is 46022877.

778220640 is a `hidden beast` number, since 7 + 7 + 8 + 2 + 2 + 0 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 778220595 and 778220604.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 21372 + ... + 44868.

It is an arithmetic number, because the mean of its divisors is an integer number (19244862).

Almost surely, 2^778220640 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 778220640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1385630064).

778220640 is an abundant number, since it is smaller than the sum of its proper divisors (1993039488).

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

778220640 is a wasteful number, since it uses less digits than its factorization.

778220640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23541 (or 23530 counting only the distinct ones).

The product of its (nonzero) digits is 37632, while the sum is 36.

The square root of 778220640 is about 27896.6062452048. The cubic root of 778220640 is about 919.8159051935.

The spelling of 778220640 in words is "seven hundred seventy-eight million, two hundred twenty thousand, six hundred forty".