199999121 has 4 divisors (see below), whose sum is σ = 228570432. Its totient is φ = 171427812.

The previous prime is 199999103. The next prime is 199999127. The reversal of 199999121 is 121999991.

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.

It is a cyclic number.

It is not a de Polignac number, because 199999121 - 2⁶ = 199999057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 199999121.

It is not an unprimeable number, because it can be changed into a prime (199999127) 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, 14285645 + ... + 14285658.

It is an arithmetic number, because the mean of its divisors is an integer number (57142608).

Almost surely, 2^199999121 is an apocalyptic number.

It is an amenable number.

199999121 is a deficient number, since it is larger than the sum of its proper divisors (28571311).

199999121 is an equidigital number, since it uses as much as digits as its factorization.

199999121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28571310.

The product of its digits is 118098, while the sum is 50.

The square root of 199999121 is about 14142.1045463538. The cubic root of 199999121 is about 584.8026909041.

The spelling of 199999121 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, one hundred twenty-one".