1688968891 has 2 divisors, whose sum is σ = 1688968892. Its totient is φ = 1688968890.

The previous prime is 1688968871. The next prime is 1688968937. The reversal of 1688968891 is 1988698861.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1688968891 - 2¹⁹ = 1688444603 is a prime.

1688968891 is a strobogrammatic number because it is the same when read upside-down.

It is not a weakly prime, because it can be changed into another prime (1688968871) 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, 844484445 + 844484446.

It is an arithmetic number, because the mean of its divisors is an integer number (844484446).

Almost surely, 2^1688968891 is an apocalyptic number.

1688968891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1688968891 is an equidigital number, since it uses as much as digits as its factorization.

1688968891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11943936, while the sum is 64.

The square root of 1688968891 is about 41097.0666958118. The cubic root of 1688968891 is about 1190.8961286642.

The spelling of 1688968891 in words is "one billion, six hundred eighty-eight million, nine hundred sixty-eight thousand, eight hundred ninety-one".