666198719 has 2 divisors, whose sum is σ = 666198720. Its totient is φ = 666198718.

The previous prime is 666198713. The next prime is 666198739. The reversal of 666198719 is 917891666.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666198719 is a prime.

It is a super-2 number, since 2×666198719² = 887641466394481922, 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 (666198713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333099359 + 333099360.

It is an arithmetic number, because the mean of its divisors is an integer number (333099360).

Almost surely, 2^666198719 is an apocalyptic number.

666198719 is a deficient number, since it is larger than the sum of its proper divisors (1).

666198719 is an equidigital number, since it uses as much as digits as its factorization.

666198719 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 979776, while the sum is 53.

The square root of 666198719 is about 25810.8256163959. The cubic root of 666198719 is about 873.3760219245.

The spelling of 666198719 in words is "six hundred sixty-six million, one hundred ninety-eight thousand, seven hundred nineteen".