199988681 has 2 divisors, whose sum is σ = 199988682. Its totient is φ = 199988680.

The previous prime is 199988653. The next prime is 199988717. The reversal of 199988681 is 186889991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 130416400 + 69572281 = 11420^2 + 8341^2 .

It is an emirp because it is prime and its reverse (186889991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199988681 - 2¹⁰ = 199987657 is a prime.

It is a super-2 number, since 2×199988681² = 79990945056239522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 199988681.

It is not a weakly prime, because it can be changed into another prime (199988081) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99994340 + 99994341.

It is an arithmetic number, because the mean of its divisors is an integer number (99994341).

Almost surely, 2^199988681 is an apocalyptic number.

It is an amenable number.

199988681 is a deficient number, since it is larger than the sum of its proper divisors (1).

199988681 is an equidigital number, since it uses as much as digits as its factorization.

199988681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2239488, while the sum is 59.

The square root of 199988681 is about 14141.7354309858. The cubic root of 199988681 is about 584.7925151155.

The spelling of 199988681 in words is "one hundred ninety-nine million, nine hundred eighty-eight thousand, six hundred eighty-one".