199988696681 has 2 divisors, whose sum is σ = 199988696682. Its totient is φ = 199988696680.

The previous prime is 199988696639. The next prime is 199988696683. The reversal of 199988696681 is 186696889991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 165286968025 + 34701728656 = 406555^2 + 186284^2 .

It is an emirp because it is prime and its reverse (186696889991) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 189969886661 and 166688969981.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199988696681 is a prime.

It is a super-2 number, since 2×199988696681² (a number of 23 digits) contains 22 as substring.

Together with 199988696683, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 199988696596 and 199988696605.

It is not a weakly prime, because it can be changed into another prime (199988696683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99994348340 + 99994348341.

It is an arithmetic number, because the mean of its divisors is an integer number (99994348341).

Almost surely, 2^199988696681 is an apocalyptic number.

It is an amenable number.

199988696681 is a deficient number, since it is larger than the sum of its proper divisors (1).

199988696681 is an equidigital number, since it uses as much as digits as its factorization.

199988696681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 725594112, while the sum is 80.

The spelling of 199988696681 in words is "one hundred ninety-nine billion, nine hundred eighty-eight million, six hundred ninety-six thousand, six hundred eighty-one".