199208921 has 4 divisors (see below), whose sum is σ = 200322000. Its totient is φ = 198095844.

The previous prime is 199208909. The next prime is 199208951. The reversal of 199208921 is 129802991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 129802991 = 269 ⋅482539.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199208921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199208951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 556271 + ... + 556628.

It is an arithmetic number, because the mean of its divisors is an integer number (50080500).

Almost surely, 2^199208921 is an apocalyptic number.

It is an amenable number.

199208921 is a deficient number, since it is larger than the sum of its proper divisors (1113079).

199208921 is a wasteful number, since it uses less digits than its factorization.

199208921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1113078.

The product of its (nonzero) digits is 23328, while the sum is 41.

The square root of 199208921 is about 14114.1390456521. The cubic root of 199208921 is about 584.0314858001.

The spelling of 199208921 in words is "one hundred ninety-nine million, two hundred eight thousand, nine hundred twenty-one".