609669821 has 2 divisors, whose sum is σ = 609669822. Its totient is φ = 609669820.

The previous prime is 609669803. The next prime is 609669857. The reversal of 609669821 is 128966906.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 569347321 + 40322500 = 23861^2 + 6350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-609669821 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (609669421) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 304834910 + 304834911.

It is an arithmetic number, because the mean of its divisors is an integer number (304834911).

Almost surely, 2^609669821 is an apocalyptic number.

It is an amenable number.

609669821 is a deficient number, since it is larger than the sum of its proper divisors (1).

609669821 is an equidigital number, since it uses as much as digits as its factorization.

609669821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 279936, while the sum is 47.

The square root of 609669821 is about 24691.4928872274. The cubic root of 609669821 is about 847.9395635439.

The spelling of 609669821 in words is "six hundred nine million, six hundred sixty-nine thousand, eight hundred twenty-one".