7780 has 12 divisors (see below), whose sum is σ = 16380. Its totient is φ = 3104.

The previous prime is 7759. The next prime is 7789. The reversal of 7780 is 877.

It can be written as a sum of positive squares in 2 ways, for example, as 2304 + 5476 = 48^2 + 74^2 .

It is a plaindrome in base 15.

It is a nialpdrome in base 5.

It is not an unprimeable number, because it can be changed into a prime (7789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 175 + ... + 214.

It is an arithmetic number, because the mean of its divisors is an integer number (1365).

2⁷⁷⁸⁰ is an apocalyptic number.

It is an amenable number.

7780 is an abundant number, since it is smaller than the sum of its proper divisors (8600).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (8190).

7780 is a wasteful number, since it uses less digits than its factorization.

7780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398 (or 396 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 7780 is about 88.2043082848. The cubic root of 7780 is about 19.8149599555.

Subtracting from 7780 its reverse (877), we obtain a triangular number (6903 = T₁₁₇).

It can be divided in two parts, 7 and 780, that multiplied together give a triangular number (5460 = T₁₀₄).

The spelling of 7780 in words is "seven thousand, seven hundred eighty".