666075661 has 2 divisors, whose sum is σ = 666075662. Its totient is φ = 666075660.

The previous prime is 666075499. The next prime is 666075667. The reversal of 666075661 is 166570666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 665949636 + 126025 = 25806^2 + 355^2 .

It is a cyclic number.

It is not a de Polignac number, because 666075661 - 2¹³ = 666067469 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (666075667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333037830 + 333037831.

It is an arithmetic number, because the mean of its divisors is an integer number (333037831).

Almost surely, 2^666075661 is an apocalyptic number.

It is an amenable number.

666075661 is a deficient number, since it is larger than the sum of its proper divisors (1).

666075661 is an equidigital number, since it uses as much as digits as its factorization.

666075661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 272160, while the sum is 43.

The square root of 666075661 is about 25808.4416615959. The cubic root of 666075661 is about 873.3222429135.

The spelling of 666075661 in words is "six hundred sixty-six million, seventy-five thousand, six hundred sixty-one".