1968688681 has 2 divisors, whose sum is σ = 1968688682. Its totient is φ = 1968688680.

The previous prime is 1968688663. The next prime is 1968688727. The reversal of 1968688681 is 1868868691.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1551099456 + 417589225 = 39384^2 + 20435^2 .

It is an emirp because it is prime and its reverse (1868868691) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 1898898961 and 1698988981.

It is a cyclic number.

It is not a de Polignac number, because 1968688681 - 2²⁹ = 1431817769 is a prime.

It is a super-2 number, since 2×1968688681² = 7751470245395039522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1968688081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 984344340 + 984344341.

It is an arithmetic number, because the mean of its divisors is an integer number (984344341).

Almost surely, 2^1968688681 is an apocalyptic number.

It is an amenable number.

1968688681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1968688681 is an equidigital number, since it uses as much as digits as its factorization.

1968688681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7962624, while the sum is 61.

The square root of 1968688681 is about 44369.9073810167. The cubic root of 1968688681 is about 1253.3114715249.

The spelling of 1968688681 in words is "one billion, nine hundred sixty-eight million, six hundred eighty-eight thousand, six hundred eighty-one".