491569 has 4 divisors (see below), whose sum is σ = 529396. Its totient is φ = 453744.

The previous prime is 491539. The next prime is 491581. The reversal of 491569 is 965194.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 965194 = 2 ⋅482597.

It can be written as a sum of positive squares in 2 ways, for example, as 19600 + 471969 = 140^2 + 687^2 .

It is a cyclic number.

It is not a de Polignac number, because 491569 - 2⁵ = 491537 is a prime.

It is a super-4 number, since 4×491569⁴ (a number of 24 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491539) 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 3 ways as a sum of consecutive naturals, for example, 18894 + ... + 18919.

It is an arithmetic number, because the mean of its divisors is an integer number (132349).

2⁴⁹¹⁵⁶⁹ is an apocalyptic number.

It is an amenable number.

491569 is a deficient number, since it is larger than the sum of its proper divisors (37827).

491569 is a wasteful number, since it uses less digits than its factorization.

491569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 37826.

The product of its digits is 9720, while the sum is 34.

The square root of 491569 is about 701.1198185760. The cubic root of 491569 is about 78.9214087826.

The spelling of 491569 in words is "four hundred ninety-one thousand, five hundred sixty-nine".