19819 has 2 divisors, whose sum is σ = 19820.
Its totient is φ = 19818.
The previous prime is 19813. The next prime is 19841. The reversal of 19819 is 91891.
It is a weak prime.
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-19819 is a prime.
It is a super-2 number, since 2×198192 = 785585522, which contains 22 as substring.
It is a Chen prime.
It is not a weakly prime, because it can be changed into another prime (19813) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9909 + 9910.
It is an arithmetic number, because the mean of its divisors is an integer number (9910).
219819 is an apocalyptic number.
19819 is a deficient number, since it is larger than the sum of its proper divisors (1).
19819 is an equidigital number, since it uses as much as digits as its factorization.
19819 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 648, while the sum is 28.
The square root of 19819 is about 140.7799701662.
The cubic root of 19819 is about 27.0620429655.
Subtracting from 19819 its sum of digits (28), we obtain a palindrome (19791).
It can be divided in two parts, 19 and 819, that added together give a palindrome (838).
The spelling of 19819 in words is "nineteen thousand, eight hundred nineteen".