865491 has 8 divisors (see below), whose sum is σ = 1258944. Its totient is φ = 524520.

The previous prime is 865483. The next prime is 865493. The reversal of 865491 is 194568.

865491 is nontrivially palindromic in base 8.

865491 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 865491 - 2³ = 865483 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33), and also a Moran number because the ratio is a prime number: 26227 = 865491 / (8 + 6 + 5 + 4 + 9 + 1).

It is an Ulam number.

865491 is an undulating number in base 8.

It is not an unprimeable number, because it can be changed into a prime (865493) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13081 + ... + 13146.

It is an arithmetic number, because the mean of its divisors is an integer number (157368).

2⁸⁶⁵⁴⁹¹ is an apocalyptic number.

865491 is a deficient number, since it is larger than the sum of its proper divisors (393453).

865491 is a wasteful number, since it uses less digits than its factorization.

865491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26241.

The product of its digits is 8640, while the sum is 33.

The square root of 865491 is about 930.3176876745. The cubic root of 865491 is about 95.2988190164.

The spelling of 865491 in words is "eight hundred sixty-five thousand, four hundred ninety-one".