199986601981 has 2 divisors, whose sum is σ = 199986601982. Its totient is φ = 199986601980.

The previous prime is 199986601949. The next prime is 199986602009. The reversal of 199986601981 is 189106689991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 198269825625 + 1716776356 = 445275^2 + 41434^2 .

It is an emirp because it is prime and its reverse (189106689991) is a distict prime. It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 186109986661 and 166689901681.

It is a cyclic number.

It is not a de Polignac number, because 199986601981 - 2⁵ = 199986601949 is a prime.

It is a super-2 number, since 2×199986601981² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199986601781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99993300990 + 99993300991.

It is an arithmetic number, because the mean of its divisors is an integer number (99993300991).

Almost surely, 2^199986601981 is an apocalyptic number.

It is an amenable number.

199986601981 is a deficient number, since it is larger than the sum of its proper divisors (1).

199986601981 is an equidigital number, since it uses as much as digits as its factorization.

199986601981 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15116544, while the sum is 67.

The spelling of 199986601981 in words is "one hundred ninety-nine billion, nine hundred eighty-six million, six hundred one thousand, nine hundred eighty-one".