691384321 has 2 divisors, whose sum is σ = 691384322. Its totient is φ = 691384320.

The previous prime is 691384313. The next prime is 691384349. The reversal of 691384321 is 123483196.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 380250000 + 311134321 = 19500^2 + 17639^2 .

It is a cyclic number.

It is not a de Polignac number, because 691384321 - 2³ = 691384313 is a prime.

It is not a weakly prime, because it can be changed into another prime (691384391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345692160 + 345692161.

It is an arithmetic number, because the mean of its divisors is an integer number (345692161).

Almost surely, 2^691384321 is an apocalyptic number.

It is an amenable number.

691384321 is a deficient number, since it is larger than the sum of its proper divisors (1).

691384321 is an equidigital number, since it uses as much as digits as its factorization.

691384321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 37.

The square root of 691384321 is about 26294.1879699678. The cubic root of 691384321 is about 884.2461457870.

The spelling of 691384321 in words is "six hundred ninety-one million, three hundred eighty-four thousand, three hundred twenty-one".