1688683681 has 2 divisors, whose sum is σ = 1688683682. Its totient is φ = 1688683680.

The previous prime is 1688683651. The next prime is 1688683693. The reversal of 1688683681 is 1863868861.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1299963025 + 388720656 = 36055^2 + 19716^2 .

It is a cyclic number.

It is not a de Polignac number, because 1688683681 - 2¹⁵ = 1688650913 is a prime.

It is a super-2 number, since 2×1688683681² = 5703305148951419522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1688683651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 844341840 + 844341841.

It is an arithmetic number, because the mean of its divisors is an integer number (844341841).

Almost surely, 2^1688683681 is an apocalyptic number.

It is an amenable number.

1688683681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1688683681 is an equidigital number, since it uses as much as digits as its factorization.

1688683681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2654208, while the sum is 55.

The square root of 1688683681 is about 41093.5965936300. The cubic root of 1688683681 is about 1190.8290907992.

The spelling of 1688683681 in words is "one billion, six hundred eighty-eight million, six hundred eighty-three thousand, six hundred eighty-one".