199643644225 has 9 divisors (see below), whose sum is σ = 247560889123. Its totient is φ = 159713128120.

The previous prime is 199643644219. The next prime is 199643644229. The reversal of 199643644225 is 522446346991.

The square root of 199643644225 is 446815.

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., 71871711921 + 127771932304 = 268089^2 + 357452^2 .

It is not a de Polignac number, because 199643644225 - 2²⁵ = 199610089793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199643644229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2189394 + ... + 2278756.

Almost surely, 2^199643644225 is an apocalyptic number.

199643644225 is the 446815-th square number.

199643644225 is the 223408-th centered octagonal number.

It is an amenable number.

199643644225 is a deficient number, since it is larger than the sum of its proper divisors (47917244898).

199643644225 is an frugal number, since it uses more digits than its factorization.

199643644225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178736 (or 89368 counting only the distinct ones).

The product of its digits is 11197440, while the sum is 55.

The spelling of 199643644225 in words is "one hundred ninety-nine billion, six hundred forty-three million, six hundred forty-four thousand, two hundred twenty-five".