199718721 has 6 divisors (see below), whose sum is σ = 288482610. Its totient is φ = 133145808.

The previous prime is 199718699. The next prime is 199718767. The reversal of 199718721 is 127817991.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 177023025 + 22695696 = 13305^2 + 4764^2 .

It is not a de Polignac number, because 199718721 - 2⁵ = 199718689 is a prime.

It is not an unprimeable number, because it can be changed into a prime (199718021) 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 5 ways as a sum of consecutive naturals, for example, 11095476 + ... + 11095493.

It is an arithmetic number, because the mean of its divisors is an integer number (48080435).

Almost surely, 2^199718721 is an apocalyptic number.

It is an amenable number.

199718721 is a deficient number, since it is larger than the sum of its proper divisors (88763889).

199718721 is a wasteful number, since it uses less digits than its factorization.

199718721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22190975 (or 22190972 counting only the distinct ones).

The product of its digits is 63504, while the sum is 45.

The square root of 199718721 is about 14132.1874103056. The cubic root of 199718721 is about 584.5292640902.

The spelling of 199718721 in words is "one hundred ninety-nine million, seven hundred eighteen thousand, seven hundred twenty-one".