666490109 has 2 divisors, whose sum is σ = 666490110. Its totient is φ = 666490108.

The previous prime is 666490103. The next prime is 666490133. The reversal of 666490109 is 901094666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 449016100 + 217474009 = 21190^2 + 14747^2 .

It is a cyclic number.

It is not a de Polignac number, because 666490109 - 2²⁰ = 665441533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666490103) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333245054 + 333245055.

It is an arithmetic number, because the mean of its divisors is an integer number (333245055).

Almost surely, 2^666490109 is an apocalyptic number.

It is an amenable number.

666490109 is a deficient number, since it is larger than the sum of its proper divisors (1).

666490109 is an equidigital number, since it uses as much as digits as its factorization.

666490109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 69984, while the sum is 41.

The square root of 666490109 is about 25816.4697238023. The cubic root of 666490109 is about 873.5033392631.

The spelling of 666490109 in words is "six hundred sixty-six million, four hundred ninety thousand, one hundred nine".