865691 has 4 divisors (see below), whose sum is σ = 916632. Its totient is φ = 814752.

The previous prime is 865687. The next prime is 865717. The reversal of 865691 is 196568.

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 865691 - 2² = 865687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (865661) 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, 25445 + ... + 25478.

It is an arithmetic number, because the mean of its divisors is an integer number (229158).

2⁸⁶⁵⁶⁹¹ is an apocalyptic number.

865691 is a deficient number, since it is larger than the sum of its proper divisors (50941).

865691 is a wasteful number, since it uses less digits than its factorization.

865691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 50940.

The product of its digits is 12960, while the sum is 35.

The square root of 865691 is about 930.4251716285. The cubic root of 865691 is about 95.3061590873.

The spelling of 865691 in words is "eight hundred sixty-five thousand, six hundred ninety-one".