664187591 has 2 divisors, whose sum is σ = 664187592. Its totient is φ = 664187590.

The previous prime is 664187519. The next prime is 664187611. The reversal of 664187591 is 195781466.

Together with previous prime (664187519) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-664187591 is a prime.

It is a super-2 number, since 2×664187591² = 882290312076766562, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664187191) 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, 332093795 + 332093796.

It is an arithmetic number, because the mean of its divisors is an integer number (332093796).

Almost surely, 2^664187591 is an apocalyptic number.

664187591 is a deficient number, since it is larger than the sum of its proper divisors (1).

664187591 is an equidigital number, since it uses as much as digits as its factorization.

664187591 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 362880, while the sum is 47.

The square root of 664187591 is about 25771.8371677302. The cubic root of 664187591 is about 872.4962837038.

The spelling of 664187591 in words is "six hundred sixty-four million, one hundred eighty-seven thousand, five hundred ninety-one".