491531 has 2 divisors, whose sum is σ = 491532. Its totient is φ = 491530.

The previous prime is 491527. The next prime is 491537. The reversal of 491531 is 135194.

It is a happy number.

491531 is nontrivially palindromic in base 5.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 491531 - 2² = 491527 is a prime.

It is a super-2 number, since 2×491531² = 483205447922, which contains 22 as substring.

It is a Sophie Germain prime.

It is a junction number, because it is equal to n+sod(n) for n = 491497 and 491506.

It is not a weakly prime, because it can be changed into another prime (491537) 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 as a sum of consecutive naturals, namely, 245765 + 245766.

It is an arithmetic number, because the mean of its divisors is an integer number (245766).

2⁴⁹¹⁵³¹ is an apocalyptic number.

491531 is a deficient number, since it is larger than the sum of its proper divisors (1).

491531 is an equidigital number, since it uses as much as digits as its factorization.

491531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 540, while the sum is 23.

The square root of 491531 is about 701.0927185473. The cubic root of 491531 is about 78.9193750967.

The spelling of 491531 in words is "four hundred ninety-one thousand, five hundred thirty-one".