666698497 has 2 divisors, whose sum is σ = 666698498. Its totient is φ = 666698496.

The previous prime is 666698453. The next prime is 666698507. The reversal of 666698497 is 794896666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 538193601 + 128504896 = 23199^2 + 11336^2 .

It is a cyclic number.

It is not a de Polignac number, because 666698497 - 2¹⁵ = 666665729 is a prime.

It is not a weakly prime, because it can be changed into another prime (666699497) 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, 333349248 + 333349249.

It is an arithmetic number, because the mean of its divisors is an integer number (333349249).

Almost surely, 2^666698497 is an apocalyptic number.

It is an amenable number.

666698497 is a deficient number, since it is larger than the sum of its proper divisors (1).

666698497 is an equidigital number, since it uses as much as digits as its factorization.

666698497 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 23514624, while the sum is 61.

The square root of 666698497 is about 25820.5053591133. The cubic root of 666698497 is about 873.5943676937.

The spelling of 666698497 in words is "six hundred sixty-six million, six hundred ninety-eight thousand, four hundred ninety-seven".