20011 has 2 divisors, whose sum is σ = 20012.
Its totient is φ = 20010.
The previous prime is 19997. The next prime is 20021. The reversal of 20011 is 11002.
20011 = T114 + T115 +
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 20011 - 25 = 19979 is a prime.
20011 is a modest number, since divided by 11 gives 2 as remainder.
It is a plaindrome in base 7.
It is not a weakly prime, because it can be changed into another prime (20021) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10005 + 10006.
It is an arithmetic number, because the mean of its divisors is an integer number (10006).
220011 is an apocalyptic number.
20011 is the 116-th centered triangular number.
20011 is a deficient number, since it is larger than the sum of its proper divisors (1).
20011 is an equidigital number, since it uses as much as digits as its factorization.
20011 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 2, while the sum is 4.
The square root of 20011 is about 141.4602417642.
The cubic root of 20011 is about 27.1491516862.
Adding to 20011 its reverse (11002), we get a palindrome (31013).
Subtracting from 20011 its reverse (11002), we obtain a palindrome (9009).
Multiplying 20011 by its reverse (11002), we get a palindrome (220161022).
It can be divided in two parts, 2001 and 1, that added together give a palindrome (2002).
The spelling of 20011 in words is "twenty thousand, eleven", and thus it is an iban number.