666261756016009 has 2 divisors, whose sum is σ = 666261756016010. Its totient is φ = 666261756016008.

The previous prime is 666261756015991. The next prime is 666261756016039. The reversal of 666261756016009 is 900610657162666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 501669149712784 + 164592606303225 = 22397972^2 + 12829365^2 .

It is a cyclic number.

It is not a de Polignac number, because 666261756016009 - 2²³ = 666261747627401 is a prime.

It is not a weakly prime, because it can be changed into another prime (666261756016039) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333130878008004 + 333130878008005.

It is an arithmetic number, because the mean of its divisors is an integer number (333130878008005).

Almost surely, 2^{666261756016009} is an apocalyptic number.

It is an amenable number.

666261756016009 is a deficient number, since it is larger than the sum of its proper divisors (1).

666261756016009 is an equidigital number, since it uses as much as digits as its factorization.

666261756016009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 29393280, while the sum is 61.

The spelling of 666261756016009 in words is "six hundred sixty-six trillion, two hundred sixty-one billion, seven hundred fifty-six million, sixteen thousand, nine".