19906 has 8 divisors (see below), whose sum is σ = 30780. Its totient is φ = 9648.

The previous prime is 19891. The next prime is 19913. The reversal of 19906 is 60991.

19906 is nontrivially palindromic in base 5.

It can be written as a sum of positive squares in 2 ways, for example, as 19881 + 25 = 141^2 + 5^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

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, 61 + ... + 208.

2¹⁹⁹⁰⁶ is an apocalyptic number.

19906 is a deficient number, since it is larger than the sum of its proper divisors (10874).

19906 is a wasteful number, since it uses less digits than its factorization.

19906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 308.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 19906 is about 141.0886246301. The cubic root of 19906 is about 27.1015834916.

Subtracting from 19906 its sum of digits (25), we obtain a square (19881 = 141²).

The spelling of 19906 in words is "nineteen thousand, nine hundred six".