765 has 12 divisors (see below), whose sum is σ = 1404. Its totient is φ = 384.

The previous prime is 761. The next prime is 769. The reversal of 765 is 567.

765 is nontrivially palindromic in base 2 and base 11.

765 is an esthetic number in base 10, because in such base its adjacent digits differ by 1.

It is an interprime number because it is at equal distance from previous prime (761) and next prime (769).

It can be written as a sum of positive squares in 2 ways, for example, as 441 + 324 = 21^2 + 18^2 .

It is not a de Polignac number, because 765 - 2^{2} = 761 is a prime.

It is an alternating number because its digits alternate between odd and even.

765 is an undulating number in base 11.

It is a Curzon number.

It is a straight-line number, since its digits are in arithmetic progression.

It is a plaindrome in base 13.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (761) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37 + ... + 53.

It is an arithmetic number, because the mean of its divisors is an integer number (117).

It is an amenable number.

765 is a deficient number, since it is larger than the sum of its proper divisors (639).

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

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

The sum of its prime factors is 28 (or 25 counting only the distinct ones).

The product of its digits is 210, while the sum is 18.

The square root of 765 is about 27.6586333719. The cubic root of 765 is about 9.1457742738.

Subtracting from 765 its sum of digits (18), we obtain a palindrome (747).

Subtracting from 765 its product of digits (210), we obtain a palindrome (555).

It can be divided in two parts, 76 and 5, that added together give a 4-th power (81 = 3^{4}).

The spelling of 765 in words is "seven hundred sixty-five", and thus it is an aban number and an oban number.

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