694638809 has 2 divisors, whose sum is σ = 694638810. Its totient is φ = 694638808.

The previous prime is 694638787. The next prime is 694638811. The reversal of 694638809 is 908836496.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 347934409 + 346704400 = 18653^2 + 18620^2 .

It is a cyclic number.

It is not a de Polignac number, because 694638809 - 2¹² = 694634713 is a prime.

It is a Sophie Germain prime.

Together with 694638811, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (694638839) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 347319404 + 347319405.

It is an arithmetic number, because the mean of its divisors is an integer number (347319405).

Almost surely, 2^694638809 is an apocalyptic number.

It is an amenable number.

694638809 is a deficient number, since it is larger than the sum of its proper divisors (1).

694638809 is an equidigital number, since it uses as much as digits as its factorization.

694638809 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2239488, while the sum is 53.

The square root of 694638809 is about 26356.0013848839. The cubic root of 694638809 is about 885.6314172098.

The spelling of 694638809 in words is "six hundred ninety-four million, six hundred thirty-eight thousand, eight hundred nine".