199968581 has 2 divisors, whose sum is σ = 199968582. Its totient is φ = 199968580.

The previous prime is 199968577. The next prime is 199968583. The reversal of 199968581 is 185869991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 134908225 + 65060356 = 11615^2 + 8066^2 .

It is a cyclic number.

It is not a de Polignac number, because 199968581 - 2² = 199968577 is a prime.

It is a super-2 number, since 2×199968581² = 79974866774307122, which contains 22 as substring.

Together with 199968583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199968583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99984290 + 99984291.

It is an arithmetic number, because the mean of its divisors is an integer number (99984291).

Almost surely, 2^199968581 is an apocalyptic number.

It is an amenable number.

199968581 is a deficient number, since it is larger than the sum of its proper divisors (1).

199968581 is an equidigital number, since it uses as much as digits as its factorization.

199968581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1399680, while the sum is 56.

The square root of 199968581 is about 14141.0247507032. The cubic root of 199968581 is about 584.7729228011.

The spelling of 199968581 in words is "one hundred ninety-nine million, nine hundred sixty-eight thousand, five hundred eighty-one".