20099 has 4 divisors (see below), whose sum is σ = 20400. Its totient is φ = 19800.

The previous prime is 20089. The next prime is 20101. The reversal of 20099 is 99002.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 20099 - 2⁸ = 19843 is a prime.

It is a Duffinian number.

20099 is a modest number, since divided by 99 gives 2 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 20099.

It is not an unprimeable number, because it can be changed into a prime (20029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2 + ... + 200.

It is an arithmetic number, because the mean of its divisors is an integer number (5100).

2²⁰⁰⁹⁹ is an apocalyptic number.

20099 is a deficient number, since it is larger than the sum of its proper divisors (301).

20099 is a wasteful number, since it uses less digits than its factorization.

20099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 20099 is about 141.7709420156. The cubic root of 20099 is about 27.1888903592.

It can be divided in two parts, 2009 and 9, that multiplied together give a palindrome (18081).

The spelling of 20099 in words is "twenty thousand, ninety-nine".