7891 has 4 divisors (see below), whose sum is σ = 8512. Its totient is φ = 7272.

The previous prime is 7883. The next prime is 7901. The reversal of 7891 is 1987.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 7891 - 2³ = 7883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7841) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 291 + ... + 316.

It is an arithmetic number, because the mean of its divisors is an integer number (2128).

2⁷⁸⁹¹ is an apocalyptic number.

7891 is a deficient number, since it is larger than the sum of its proper divisors (621).

7891 is a wasteful number, since it uses less digits than its factorization.

7891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 620.

The product of its digits is 504, while the sum is 25.

The square root of 7891 is about 88.8313007898. The cubic root of 7891 is about 19.9087509806.

It can be divided in two parts, 78 and 91, that added together give a square (169 = 13²).

The spelling of 7891 in words is "seven thousand, eight hundred ninety-one".