668660249 has 6 divisors (see below), whose sum is σ = 672216090. Its totient is φ = 665123120.

The previous prime is 668660233. The next prime is 668660327. The reversal of 668660249 is 942066866.

It can be written as a sum of positive squares in only one way, i.e., 570015625 + 98644624 = 23875^2 + 9932^2 .

It is not a de Polignac number, because 668660249 - 2⁴ = 668660233 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668660219) 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 5 ways as a sum of consecutive naturals, for example, 27317 + ... + 45645.

It is an arithmetic number, because the mean of its divisors is an integer number (112036015).

Almost surely, 2^668660249 is an apocalyptic number.

It is an amenable number.

668660249 is a deficient number, since it is larger than the sum of its proper divisors (3555841).

668660249 is an equidigital number, since it uses as much as digits as its factorization.

668660249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18711 (or 18520 counting only the distinct ones).

The product of its (nonzero) digits is 746496, while the sum is 47.

The square root of 668660249 is about 25858.4657124123. The cubic root of 668660249 is about 874.4503754829.

The spelling of 668660249 in words is "six hundred sixty-eight million, six hundred sixty thousand, two hundred forty-nine".