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19811 = 111801
BaseRepresentation
bin100110101100011
31000011202
410311203
51113221
6231415
7111521
oct46543
930152
1019811
1113980
12b56b
13902c
147311
155d0b
hex4d63

19811 has 4 divisors (see below), whose sum is σ = 21624. Its totient is φ = 18000.

The previous prime is 19801. The next prime is 19813. The reversal of 19811 is 11891.

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 not a de Polignac number, because 19811 - 210 = 18787 is a prime.

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.

It is not an unprimeable number, because it can be changed into a prime (19813) 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, 890 + ... + 911.

It is an arithmetic number, because the mean of its divisors is an integer number (5406).

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 deficient number, since it is larger than the sum of its proper divisors (1813).

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 product of its digits is 72, while the sum is 20.

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".

Divisors: 1 11 1801 19811