668540969 has 2 divisors, whose sum is σ = 668540970. Its totient is φ = 668540968.

The previous prime is 668540923. The next prime is 668540987. The reversal of 668540969 is 969045866.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 614444944 + 54096025 = 24788^2 + 7355^2 .

It is a cyclic number.

It is not a de Polignac number, because 668540969 - 2²⁰ = 667492393 is a prime.

It is a super-2 number, since 2×668540969² = 893894054462917922, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 668540969.

It is not a weakly prime, because it can be changed into another prime (668543969) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334270484 + 334270485.

It is an arithmetic number, because the mean of its divisors is an integer number (334270485).

Almost surely, 2^668540969 is an apocalyptic number.

It is an amenable number.

668540969 is a deficient number, since it is larger than the sum of its proper divisors (1).

668540969 is an equidigital number, since it uses as much as digits as its factorization.

668540969 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2799360, while the sum is 53.

The square root of 668540969 is about 25856.1592082041. The cubic root of 668540969 is about 874.3983756600.

The spelling of 668540969 in words is "six hundred sixty-eight million, five hundred forty thousand, nine hundred sixty-nine".