199995889681 has 27 divisors (see below), whose sum is σ = 241056689211. Its totient is φ = 165438708624.

The previous prime is 199995889651. The next prime is 199995889777. The reversal of 199995889681 is 186988599991.

The square root of 199995889681 is 447209.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 104872993281 + 95122896400 = 323841^2 + 308420^2 .

It is not a de Polignac number, because 199995889681 - 2¹¹ = 199995887633 is a prime.

It is a super-2 number, since 2×199995889681² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 199995889595 and 199995889604.

It is not an unprimeable number, because it can be changed into a prime (199995889631) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 90782326 + ... + 90784528.

Almost surely, 2^199995889681 is an apocalyptic number.

199995889681 is the 447209-th square number.

199995889681 is the 223605-th centered octagonal number.

It is an amenable number.

199995889681 is a deficient number, since it is larger than the sum of its proper divisors (41060799530).

199995889681 is an frugal number, since it uses more digits than its factorization.

199995889681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4478 (or 2239 counting only the distinct ones).

The product of its digits is 906992640, while the sum is 82.

The spelling of 199995889681 in words is "one hundred ninety-nine billion, nine hundred ninety-five million, eight hundred eighty-nine thousand, six hundred eighty-one".