199997081 has 2 divisors, whose sum is σ = 199997082. Its totient is φ = 199997080.

The previous prime is 199997053. The next prime is 199997107. The reversal of 199997081 is 180799991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 192793225 + 7203856 = 13885^2 + 2684^2 .

It is a cyclic number.

It is not a de Polignac number, because 199997081 - 2¹⁸ = 199734937 is a prime.

It is a super-2 number, since 2×199997081² = 79997664817041122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (199997041) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99998540 + 99998541.

It is an arithmetic number, because the mean of its divisors is an integer number (99998541).

Almost surely, 2^199997081 is an apocalyptic number.

It is an amenable number.

199997081 is a deficient number, since it is larger than the sum of its proper divisors (1).

199997081 is an equidigital number, since it uses as much as digits as its factorization.

199997081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 367416, while the sum is 53.

The square root of 199997081 is about 14142.0324211197. The cubic root of 199997081 is about 584.8007025595.

The spelling of 199997081 in words is "one hundred ninety-nine million, nine hundred ninety-seven thousand, eighty-one".