491665 has 8 divisors (see below), whose sum is σ = 596160. Its totient is φ = 389232.

The previous prime is 491653. The next prime is 491669. The reversal of 491665 is 566194.

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

It is a cyclic number.

It is not a de Polignac number, because 491665 - 2⁵ = 491633 is a prime.

491665 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491669) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 76 + ... + 994.

It is an arithmetic number, because the mean of its divisors is an integer number (74520).

2⁴⁹¹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

491665 is a deficient number, since it is larger than the sum of its proper divisors (104495).

491665 is a wasteful number, since it uses less digits than its factorization.

491665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1031.

The product of its digits is 6480, while the sum is 31.

The square root of 491665 is about 701.1882771410. The cubic root of 491665 is about 78.9265460485.

Subtracting 491665 from its reverse (566194), we obtain a square (74529 = 273²).

It can be divided in two parts, 491 and 665, that added together give a square (1156 = 34²).

The spelling of 491665 in words is "four hundred ninety-one thousand, six hundred sixty-five".