199989100681 has 2 divisors, whose sum is σ = 199989100682. Its totient is φ = 199989100680.

The previous prime is 199989100657. The next prime is 199989100691. The reversal of 199989100681 is 186001989991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 196795155456 + 3193945225 = 443616^2 + 56515^2 .

It is an emirp because it is prime and its reverse (186001989991) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 189001686661 and 166686100981.

It is a cyclic number.

It is not a de Polignac number, because 199989100681 - 2²³ = 199980712073 is a prime.

It is a super-2 number, since 2×199989100681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (199989100651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99994550340 + 99994550341.

It is an arithmetic number, because the mean of its divisors is an integer number (99994550341).

Almost surely, 2^199989100681 is an apocalyptic number.

It is an amenable number.

199989100681 is a deficient number, since it is larger than the sum of its proper divisors (1).

199989100681 is an equidigital number, since it uses as much as digits as its factorization.

199989100681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2519424, while the sum is 61.

The spelling of 199989100681 in words is "one hundred ninety-nine billion, nine hundred eighty-nine million, one hundred thousand, six hundred eighty-one".