491861 has 4 divisors (see below), whose sum is σ = 520812. Its totient is φ = 462912.

The previous prime is 491857. The next prime is 491867. The reversal of 491861 is 168194.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 323761 + 168100 = 569^2 + 410^2 .

It is a cyclic number.

It is not a de Polignac number, because 491861 - 2² = 491857 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491867) 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, 14450 + ... + 14483.

It is an arithmetic number, because the mean of its divisors is an integer number (130203).

2⁴⁹¹⁸⁶¹ is an apocalyptic number.

It is an amenable number.

491861 is a deficient number, since it is larger than the sum of its proper divisors (28951).

491861 is a wasteful number, since it uses less digits than its factorization.

491861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28950.

The product of its digits is 1728, while the sum is 29.

The square root of 491861 is about 701.3280259622. The cubic root of 491861 is about 78.9370325572.

The spelling of 491861 in words is "four hundred ninety-one thousand, eight hundred sixty-one".