Subtracting from 19811 its sum of digits (20), we obtain a palindrome (19791).
It is a semiprime because it is the product of two primes.
It is a cyclic number.
It is a Duffinian number.
It is a nialpdrome in base 14.
It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 19811.
219811 is an apocalyptic number.
19811 is a gapful number since it is divisible by the number (11) formed by its first and last digit.
19811 is a wasteful number, since it uses less digits than its factorization.
19811 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 1812.
The square root of 19811 is about 140.7515541655. The cubic root of 19811 is about 27.0584012499.
The spelling of 19811 in words is "nineteen thousand, eight hundred eleven".