7765 has 4 divisors (see below), whose sum is σ = 9324. Its totient is φ = 6208.

The previous prime is 7759. The next prime is 7789. The reversal of 7765 is 5677.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5677 = 7 ⋅811.

It can be written as a sum of positive squares in 2 ways, for example, as 1681 + 6084 = 41^2 + 78^2 .

It is a cyclic number.

It is not a de Polignac number, because 7765 - 2³ = 7757 is a prime.

It is a Duffinian number.

It is a plaindrome in base 9 and base 15.

It is a nialpdrome in base 6 and base 10.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 772 + ... + 781.

It is an arithmetic number, because the mean of its divisors is an integer number (2331).

It is an amenable number.

7765 is a deficient number, since it is larger than the sum of its proper divisors (1559).

7765 is a wasteful number, since it uses less digits than its factorization.

7765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1558.

The product of its digits is 1470, while the sum is 25.

The square root of 7765 is about 88.1192374002. The cubic root of 7765 is about 19.8022172125.

It can be divided in two parts, 77 and 65, that multiplied together give a palindrome (5005).

The spelling of 7765 in words is "seven thousand, seven hundred sixty-five".