199763981 has 2 divisors, whose sum is σ = 199763982. Its totient is φ = 199763980.

The previous prime is 199763953. The next prime is 199763983. The reversal of 199763981 is 189367991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 178649956 + 21114025 = 13366^2 + 4595^2 .

It is a cyclic number.

It is not a de Polignac number, because 199763981 - 2¹⁰ = 199762957 is a prime.

It is a super-3 number, since 3×199763981³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

Together with 199763983, 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 (199763983) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99881990 + 99881991.

It is an arithmetic number, because the mean of its divisors is an integer number (99881991).

Almost surely, 2^199763981 is an apocalyptic number.

It is an amenable number.

199763981 is a deficient number, since it is larger than the sum of its proper divisors (1).

199763981 is an equidigital number, since it uses as much as digits as its factorization.

199763981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 734832, while the sum is 53.

The square root of 199763981 is about 14133.7886286728. The cubic root of 199763981 is about 584.5734158455.

The spelling of 199763981 in words is "one hundred ninety-nine million, seven hundred sixty-three thousand, nine hundred eighty-one".