1688305391 has 2 divisors, whose sum is σ = 1688305392. Its totient is φ = 1688305390.

The previous prime is 1688305369. The next prime is 1688305393. The reversal of 1688305391 is 1935038861.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1688305391 - 2⁶ = 1688305327 is a prime.

Together with 1688305393, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1688305393) 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, 844152695 + 844152696.

It is an arithmetic number, because the mean of its divisors is an integer number (844152696).

Almost surely, 2^1688305391 is an apocalyptic number.

1688305391 is a deficient number, since it is larger than the sum of its proper divisors (1).

1688305391 is an equidigital number, since it uses as much as digits as its factorization.

1688305391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 155520, while the sum is 44.

The square root of 1688305391 is about 41088.9935505848. The cubic root of 1688305391 is about 1190.7401630772.

The spelling of 1688305391 in words is "one billion, six hundred eighty-eight million, three hundred five thousand, three hundred ninety-one".