199729781 has 2 divisors, whose sum is σ = 199729782. Its totient is φ = 199729780.

The previous prime is 199729741. The next prime is 199729801. The reversal of 199729781 is 187927991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 163609681 + 36120100 = 12791^2 + 6010^2 .

It is an emirp because it is prime and its reverse (187927991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199729781 - 2²² = 195535477 is a prime.

It is a super-2 number, since 2×199729781² = 79783970836615922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199729721) 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, 99864890 + 99864891.

It is an arithmetic number, because the mean of its divisors is an integer number (99864891).

Almost surely, 2^199729781 is an apocalyptic number.

It is an amenable number.

199729781 is a deficient number, since it is larger than the sum of its proper divisors (1).

199729781 is an equidigital number, since it uses as much as digits as its factorization.

199729781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 571536, while the sum is 53.

The square root of 199729781 is about 14132.5787102001. The cubic root of 199729781 is about 584.5400538888.

The spelling of 199729781 in words is "one hundred ninety-nine million, seven hundred twenty-nine thousand, seven hundred eighty-one".