660870809 has 2 divisors, whose sum is σ = 660870810. Its totient is φ = 660870808.

The previous prime is 660870761. The next prime is 660870829. The reversal of 660870809 is 908078066.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 655206409 + 5664400 = 25597^2 + 2380^2 .

It is a cyclic number.

It is not a de Polignac number, because 660870809 - 2¹⁶ = 660805273 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 660870809.

It is not a weakly prime, because it can be changed into another prime (660870829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330435404 + 330435405.

It is an arithmetic number, because the mean of its divisors is an integer number (330435405).

Almost surely, 2^660870809 is an apocalyptic number.

It is an amenable number.

660870809 is a deficient number, since it is larger than the sum of its proper divisors (1).

660870809 is an equidigital number, since it uses as much as digits as its factorization.

660870809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 145152, while the sum is 44.

The square root of 660870809 is about 25707.4076678299. The cubic root of 660870809 is about 871.0415187577.

The spelling of 660870809 in words is "six hundred sixty million, eight hundred seventy thousand, eight hundred nine".