666728519 has 2 divisors, whose sum is σ = 666728520. Its totient is φ = 666728518.

The previous prime is 666728509. The next prime is 666728521. The reversal of 666728519 is 915827666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666728519 - 2²⁰ = 665679943 is a prime.

It is a super-2 number, since 2×666728519² = 889053836095866722, which contains 22 as substring.

Together with 666728521, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666728509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333364259 + 333364260.

It is an arithmetic number, because the mean of its divisors is an integer number (333364260).

Almost surely, 2^666728519 is an apocalyptic number.

666728519 is a deficient number, since it is larger than the sum of its proper divisors (1).

666728519 is an equidigital number, since it uses as much as digits as its factorization.

666728519 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1088640, while the sum is 50.

The square root of 666728519 is about 25821.0867122203. The cubic root of 666728519 is about 873.6074803959.

The spelling of 666728519 in words is "six hundred sixty-six million, seven hundred twenty-eight thousand, five hundred nineteen".