668552491 has 2 divisors, whose sum is σ = 668552492. Its totient is φ = 668552490.

The previous prime is 668552473. The next prime is 668552509. The reversal of 668552491 is 194255866.

It is a balanced prime because it is at equal distance from previous prime (668552473) and next prime (668552509).

It is a cyclic number.

It is not a de Polignac number, because 668552491 - 2⁵ = 668552459 is a prime.

It is not a weakly prime, because it can be changed into another prime (668552461) 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, 334276245 + 334276246.

It is an arithmetic number, because the mean of its divisors is an integer number (334276246).

Almost surely, 2^668552491 is an apocalyptic number.

668552491 is a deficient number, since it is larger than the sum of its proper divisors (1).

668552491 is an equidigital number, since it uses as much as digits as its factorization.

668552491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 518400, while the sum is 46.

The square root of 668552491 is about 25856.3820168252. The cubic root of 668552491 is about 874.4033989175.

The spelling of 668552491 in words is "six hundred sixty-eight million, five hundred fifty-two thousand, four hundred ninety-one".