491366591 has 4 divisors (see below), whose sum is σ = 503351184. Its totient is φ = 479382000.

The previous prime is 491366569. The next prime is 491366609. The reversal of 491366591 is 195663194.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 195663194 = 2 ⋅97831597.

It is a cyclic number.

It is not a de Polignac number, because 491366591 - 2⁶ = 491366527 is a prime.

It is a super-2 number, since 2×491366591² = 482882253501922562, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491066591) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5992235 + ... + 5992316.

It is an arithmetic number, because the mean of its divisors is an integer number (125837796).

Almost surely, 2^491366591 is an apocalyptic number.

491366591 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

491366591 is a deficient number, since it is larger than the sum of its proper divisors (11984593).

491366591 is a wasteful number, since it uses less digits than its factorization.

491366591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11984592.

The product of its digits is 174960, while the sum is 44.

The square root of 491366591 is about 22166.7902728383. The cubic root of 491366591 is about 789.1057503968.

The spelling of 491366591 in words is "four hundred ninety-one million, three hundred sixty-six thousand, five hundred ninety-one".