664085491 has 2 divisors, whose sum is σ = 664085492. Its totient is φ = 664085490.

The previous prime is 664085489. The next prime is 664085497. The reversal of 664085491 is 194580466.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 664085491 - 2¹ = 664085489 is a prime.

It is a super-2 number, since 2×664085491² = 882019078713422162, which contains 22 as substring.

Together with 664085489, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (664085497) 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 as a sum of consecutive naturals, namely, 332042745 + 332042746.

It is an arithmetic number, because the mean of its divisors is an integer number (332042746).

Almost surely, 2^664085491 is an apocalyptic number.

664085491 is a deficient number, since it is larger than the sum of its proper divisors (1).

664085491 is an equidigital number, since it uses as much as digits as its factorization.

664085491 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 207360, while the sum is 43.

The square root of 664085491 is about 25769.8562471738. The cubic root of 664085491 is about 872.4515742288.

The spelling of 664085491 in words is "six hundred sixty-four million, eighty-five thousand, four hundred ninety-one".