691666319 has 2 divisors, whose sum is σ = 691666320. Its totient is φ = 691666318.

The previous prime is 691666289. The next prime is 691666343. The reversal of 691666319 is 913666196.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691666319 is a prime.

It is a super-2 number, since 2×691666319² = 956804593678019522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691666379) 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, 345833159 + 345833160.

It is an arithmetic number, because the mean of its divisors is an integer number (345833160).

Almost surely, 2^691666319 is an apocalyptic number.

691666319 is a deficient number, since it is larger than the sum of its proper divisors (1).

691666319 is an equidigital number, since it uses as much as digits as its factorization.

691666319 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 314928, while the sum is 47.

The square root of 691666319 is about 26299.5497870211. The cubic root of 691666319 is about 884.3663499160.

The spelling of 691666319 in words is "six hundred ninety-one million, six hundred sixty-six thousand, three hundred nineteen".