669173809 has 2 divisors, whose sum is σ = 669173810. Its totient is φ = 669173808.

The previous prime is 669173789. The next prime is 669173819. The reversal of 669173809 is 908371966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 582739600 + 86434209 = 24140^2 + 9297^2 .

It is a cyclic number.

It is not a de Polignac number, because 669173809 - 2⁵ = 669173777 is a prime.

It is not a weakly prime, because it can be changed into another prime (669173819) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334586904 + 334586905.

It is an arithmetic number, because the mean of its divisors is an integer number (334586905).

Almost surely, 2^669173809 is an apocalyptic number.

It is an amenable number.

669173809 is a deficient number, since it is larger than the sum of its proper divisors (1).

669173809 is an equidigital number, since it uses as much as digits as its factorization.

669173809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 489888, while the sum is 49.

The square root of 669173809 is about 25868.3940166374. The cubic root of 669173809 is about 874.6741900997.

The spelling of 669173809 in words is "six hundred sixty-nine million, one hundred seventy-three thousand, eight hundred nine".