869 has 4 divisors (see below), whose sum is σ = 960. Its totient is φ = 780.

The previous prime is 863. The next prime is 877. The reversal of 869 is 968.

869 = 16² + 17² + 18².

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 a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 869 - 2⁴ = 853 is a prime.

It is a super-2 number, since 2×869² = 1510322, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a nialpdrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (863) 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, 29 + ... + 50.

It is an arithmetic number, because the mean of its divisors is an integer number (240).

2⁸⁶⁹ is an apocalyptic number.

It is an amenable number.

869 is a deficient number, since it is larger than the sum of its proper divisors (91).

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

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

The sum of its prime factors is 90.

The product of its digits is 432, while the sum is 23.

The square root of 869 is about 29.4788059460. The cubic root of 869 is about 9.5427436815.

Subtracting 869 from its reverse (968), we obtain a palindrome (99).

It can be divided in two parts, 8 and 69, that added together give a palindrome (77).

The spelling of 869 in words is "eight hundred sixty-nine", and thus it is an aban number and an oban number.