199901 has 4 divisors (see below), whose sum is σ = 215292. Its totient is φ = 184512.

The previous prime is 199889. The next prime is 199909. The reversal of 199901 is 109991.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 136900 + 63001 = 370^2 + 251^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199901 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199909) 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, 7676 + ... + 7701.

It is an arithmetic number, because the mean of its divisors is an integer number (53823).

2¹⁹⁹⁹⁰¹ is an apocalyptic number.

It is an amenable number.

199901 is a deficient number, since it is larger than the sum of its proper divisors (15391).

199901 is a wasteful number, since it uses less digits than its factorization.

199901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15390.

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 199901 is about 447.1028964344. The cubic root of 199901 is about 58.4707039132.

It can be divided in two parts, 19990 and 1, that added together give a palindrome (19991).

The spelling of 199901 in words is "one hundred ninety-nine thousand, nine hundred one".