669688813 has 2 divisors, whose sum is σ = 669688814. Its totient is φ = 669688812.

The previous prime is 669688783. The next prime is 669688841. The reversal of 669688813 is 318886966.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 486952489 + 182736324 = 22067^2 + 13518^2 .

It is a cyclic number.

It is not a de Polignac number, because 669688813 - 2⁵ = 669688781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (669688843) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 334844406 + 334844407.

It is an arithmetic number, because the mean of its divisors is an integer number (334844407).

Almost surely, 2^669688813 is an apocalyptic number.

It is an amenable number.

669688813 is a deficient number, since it is larger than the sum of its proper divisors (1).

669688813 is an equidigital number, since it uses as much as digits as its factorization.

669688813 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2985984, while the sum is 55.

The square root of 669688813 is about 25878.3464116238. The cubic root of 669688813 is about 874.8985190608.

The spelling of 669688813 in words is "six hundred sixty-nine million, six hundred eighty-eight thousand, eight hundred thirteen".