199057921 has 4 divisors (see below), whose sum is σ = 199354372. Its totient is φ = 198761472.

The previous prime is 199057919. The next prime is 199057973. The reversal of 199057921 is 129750991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 129750991 = 7079 ⋅18329.

It can be written as a sum of positive squares in 2 ways, for example, as 102232321 + 96825600 = 10111^2 + 9840^2 .

It is a cyclic number.

It is not a de Polignac number, because 199057921 - 2¹ = 199057919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199057021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 147216 + ... + 148561.

It is an arithmetic number, because the mean of its divisors is an integer number (49838593).

Almost surely, 2^199057921 is an apocalyptic number.

It is an amenable number.

199057921 is a deficient number, since it is larger than the sum of its proper divisors (296451).

199057921 is an equidigital number, since it uses as much as digits as its factorization.

199057921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 296450.

The product of its (nonzero) digits is 51030, while the sum is 43.

The square root of 199057921 is about 14108.7887857179. The cubic root of 199057921 is about 583.8838835649.

The spelling of 199057921 in words is "one hundred ninety-nine million, fifty-seven thousand, nine hundred twenty-one".