666691579 has 2 divisors, whose sum is σ = 666691580. Its totient is φ = 666691578.

The previous prime is 666691523. The next prime is 666691583. The reversal of 666691579 is 975196666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 666691579 - 2¹⁹ = 666167291 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (666691279) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333345789 + 333345790.

It is an arithmetic number, because the mean of its divisors is an integer number (333345790).

Almost surely, 2^666691579 is an apocalyptic number.

666691579 is a deficient number, since it is larger than the sum of its proper divisors (1).

666691579 is an equidigital number, since it uses as much as digits as its factorization.

666691579 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3674160, while the sum is 55.

The square root of 666691579 is about 25820.3713954699. The cubic root of 666691579 is about 873.5913460646.

The spelling of 666691579 in words is "six hundred sixty-six million, six hundred ninety-one thousand, five hundred seventy-nine".