199211361561 has 27 divisors (see below), whose sum is σ = 295810520733. Its totient is φ = 129186044640.

The previous prime is 199211361541. The next prime is 199211361571. The reversal of 199211361561 is 165163112991.

The square root of 199211361561 is 446331.

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

199211361561 is a `hidden beast` number, since 1 + 9 + 9 + 21 + 1 + 3 + 61 + 561 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1414136025 + 197797225536 = 37605^2 + 444744^2 .

It is not a de Polignac number, because 199211361561 - 2¹¹ = 199211359513 is a prime.

It is not an unprimeable number, because it can be changed into a prime (199211361521) 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, 49540731 + ... + 49544751.

Almost surely, 2^199211361561 is an apocalyptic number.

199211361561 is the 446331-st square number.

199211361561 is the 223166-th centered octagonal number.

It is an amenable number.

199211361561 is a deficient number, since it is larger than the sum of its proper divisors (96599159172).

199211361561 is an frugal number, since it uses more digits than its factorization.

199211361561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8122 (or 4061 counting only the distinct ones).

The product of its digits is 87480, while the sum is 45.

The spelling of 199211361561 in words is "one hundred ninety-nine billion, two hundred eleven million, three hundred sixty-one thousand, five hundred sixty-one".