7791 has 12 divisors (see below), whose sum is σ = 12312. Its totient is φ = 4368.

The previous prime is 7789. The next prime is 7793. The reversal of 7791 is 1977.

It is an interprime number because it is at equal distance from previous prime (7789) and next prime (7793).

It is not a de Polignac number, because 7791 - 2¹ = 7789 is a prime.

Its product of digits (441) is a multiple of the sum of its prime divisors (63).

7791 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7793) 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, 121 + ... + 173.

It is an arithmetic number, because the mean of its divisors is an integer number (1026).

7791 is a deficient number, since it is larger than the sum of its proper divisors (4521).

7791 is a wasteful number, since it uses less digits than its factorization.

7791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 70 (or 63 counting only the distinct ones).

The product of its digits is 441, while the sum is 24.

The square root of 7791 is about 88.2666414904. The cubic root of 7791 is about 19.8242942278.

It can be divided in two parts, 779 and 1, that added together give a triangular number (780 = T₃₉).

The spelling of 7791 in words is "seven thousand, seven hundred ninety-one".