669809191 has 2 divisors, whose sum is σ = 669809192. Its totient is φ = 669809190.

The previous prime is 669809159. The next prime is 669809213. The reversal of 669809191 is 191908966.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 669809191 - 2⁵ = 669809159 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (669809141) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334904595 + 334904596.

It is an arithmetic number, because the mean of its divisors is an integer number (334904596).

Almost surely, 2^669809191 is an apocalyptic number.

669809191 is a deficient number, since it is larger than the sum of its proper divisors (1).

669809191 is an equidigital number, since it uses as much as digits as its factorization.

669809191 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 209952, while the sum is 49.

The square root of 669809191 is about 25880.6721512406. The cubic root of 669809191 is about 874.9509375484.

The spelling of 669809191 in words is "six hundred sixty-nine million, eight hundred nine thousand, one hundred ninety-one".