199754469721 has 9 divisors (see below), whose sum is σ = 201687066399. Its totient is φ = 197840229984.

The previous prime is 199754469709. The next prime is 199754469731. The reversal of 199754469721 is 127964457991.

It is a happy number.

The square root of 199754469721 is 446939.

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., 184560456025 + 15194013696 = 429605^2 + 123264^2 .

It is not a de Polignac number, because 199754469721 - 2¹⁷ = 199754338649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199754469731) 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, 47820385 + ... + 47824561.

Almost surely, 2^199754469721 is an apocalyptic number.

199754469721 is the 446939-th square number.

199754469721 is the 223470-th centered octagonal number.

It is an amenable number.

199754469721 is a deficient number, since it is larger than the sum of its proper divisors (1932596678).

199754469721 is an frugal number, since it uses more digits than its factorization.

199754469721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8568 (or 4284 counting only the distinct ones).

The product of its digits is 34292160, while the sum is 64.

Multiplying 199754469721 by its sum of digits (64), we get a square (12784286062144 = 3575512²).

The spelling of 199754469721 in words is "one hundred ninety-nine billion, seven hundred fifty-four million, four hundred sixty-nine thousand, seven hundred twenty-one".