491971 has 4 divisors (see below), whose sum is σ = 496944. Its totient is φ = 487000.

The previous prime is 491969. The next prime is 491977. The reversal of 491971 is 179194.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 179194 = 2 ⋅89597.

It is a cyclic number.

It is not a de Polignac number, because 491971 - 2¹ = 491969 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491977) 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, 2335 + ... + 2536.

It is an arithmetic number, because the mean of its divisors is an integer number (124236).

2⁴⁹¹⁹⁷¹ is an apocalyptic number.

491971 is a deficient number, since it is larger than the sum of its proper divisors (4973).

491971 is a wasteful number, since it uses less digits than its factorization.

491971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4972.

The product of its digits is 2268, while the sum is 31.

The square root of 491971 is about 701.4064442247. The cubic root of 491971 is about 78.9429166223.

The spelling of 491971 in words is "four hundred ninety-one thousand, nine hundred seventy-one".