199577521081 has 9 divisors (see below), whose sum is σ = 206237493669. Its totient is φ = 193126134300.

The previous prime is 199577521069. The next prime is 199577521141. The reversal of 199577521081 is 180125775991.

The square root of 199577521081 is 446741.

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

It is not a de Polignac number, because 199577521081 - 2¹¹ = 199577519033 is a prime.

It is a super-2 number, since 2×199577521081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199577521001) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 13841766 + ... + 13856176.

Almost surely, 2^199577521081 is an apocalyptic number.

199577521081 is the 446741-st square number.

199577521081 is the 223371-st centered octagonal number.

It is an amenable number.

199577521081 is a deficient number, since it is larger than the sum of its proper divisors (6659972588).

199577521081 is an frugal number, since it uses more digits than its factorization.

199577521081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28884 (or 14442 counting only the distinct ones).

The product of its (nonzero) digits is 1587600, while the sum is 55.

The spelling of 199577521081 in words is "one hundred ninety-nine billion, five hundred seventy-seven million, five hundred twenty-one thousand, eighty-one".