491509 has 4 divisors (see below), whose sum is σ = 498316. Its totient is φ = 484704.

The previous prime is 491503. The next prime is 491527. The reversal of 491509 is 905194.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 905194 = 2 ⋅452597.

It can be written as a sum of positive squares in 2 ways, for example, as 418609 + 72900 = 647^2 + 270^2 .

It is a cyclic number.

It is not a de Polignac number, because 491509 - 2³ = 491501 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491501) 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, 3294 + ... + 3439.

It is an arithmetic number, because the mean of its divisors is an integer number (124579).

2⁴⁹¹⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

491509 is a deficient number, since it is larger than the sum of its proper divisors (6807).

491509 is an equidigital number, since it uses as much as digits as its factorization.

491509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6806.

The product of its (nonzero) digits is 1620, while the sum is 28.

The square root of 491509 is about 701.0770285782. The cubic root of 491509 is about 78.9181976517.

It can be divided in two parts, 491 and 509, that added together give a cube (1000 = 10³).

The spelling of 491509 in words is "four hundred ninety-one thousand, five hundred nine".