7861 has 4 divisors (see below), whose sum is σ = 8992. Its totient is φ = 6732.

The previous prime is 7853. The next prime is 7867. The reversal of 7861 is 1687.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 1687 = 7 ⋅241.

It is a cyclic number.

It is not a de Polignac number, because 7861 - 2³ = 7853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7867) 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, 555 + ... + 568.

It is an arithmetic number, because the mean of its divisors is an integer number (2248).

2⁷⁸⁶¹ is an apocalyptic number.

It is an amenable number.

7861 is a deficient number, since it is larger than the sum of its proper divisors (1131).

7861 is a wasteful number, since it uses less digits than its factorization.

7861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1130.

The product of its digits is 336, while the sum is 22.

The square root of 7861 is about 88.6622805933. The cubic root of 7861 is about 19.8834892469.

It can be divided in two parts, 786 and 1, that added together give a palindrome (787).

The spelling of 7861 in words is "seven thousand, eight hundred sixty-one".