7780816 has 40 divisors (see below), whose sum is σ = 16014600. Its totient is φ = 3655680.

The previous prime is 7780811. The next prime is 7780873. The reversal of 7780816 is 6180877.

7780816 = 255² + 256² + ... + 341².

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 1000000 + 6780816 = 1000^2 + 2604^2 .

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7780811) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 18820 + ... + 19228.

It is an arithmetic number, because the mean of its divisors is an integer number (400365).

Almost surely, 2^7780816 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 7780816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8007300).

7780816 is an abundant number, since it is smaller than the sum of its proper divisors (8233784).

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

7780816 is a wasteful number, since it uses less digits than its factorization.

7780816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487 (or 481 counting only the distinct ones).

The product of its (nonzero) digits is 18816, while the sum is 37.

The square root of 7780816 is about 2789.4114074478. The cubic root of 7780816 is about 198.1565269085.

The spelling of 7780816 in words is "seven million, seven hundred eighty thousand, eight hundred sixteen".