199953781 has 2 divisors, whose sum is σ = 199953782. Its totient is φ = 199953780.

The previous prime is 199953769. The next prime is 199953799. The reversal of 199953781 is 187359991.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 159516900 + 40436881 = 12630^2 + 6359^2 .

It is a cyclic number.

It is not a de Polignac number, because 199953781 - 2⁷ = 199953653 is a prime.

It is a super-2 number, since 2×199953781² = 79963029072391922, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199950781) 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, 99976890 + 99976891.

It is an arithmetic number, because the mean of its divisors is an integer number (99976891).

Almost surely, 2^199953781 is an apocalyptic number.

It is an amenable number.

199953781 is a deficient number, since it is larger than the sum of its proper divisors (1).

199953781 is an equidigital number, since it uses as much as digits as its factorization.

199953781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 612360, while the sum is 52.

The square root of 199953781 is about 14140.5014408966. The cubic root of 199953781 is about 584.7584957800.

The spelling of 199953781 in words is "one hundred ninety-nine million, nine hundred fifty-three thousand, seven hundred eighty-one".